Optimizing comparison of values in large arrays - Go - arrays

I am trying to learn Go, and made an attempt at solving the problem explained here https://projecteuler.net/problem=215
I made a solution that works, but it takes a very long time to compute once the problem gets complex, literally running for hours without solving the question so i assume i need to optimize my solution somehow. Below is my code
package main
import "fmt"
func main() {
fmt.Println(wall(18, 10))
}
func wall(width, height int) int64 {
var total int64
combinations := findCombinations(width)
combiPointer := &combinations
for i := 0; i < 4; i++ {
for _, a := range combinations[i] {
if i%2 == 0 {
buildWall(a, combiPointer[i+1], 0, height, i+1, &total, combiPointer)
} else {
buildWall(a, combiPointer[i-1], 0, height, i-1, &total, combiPointer)
}
}
}
return total
}
func buildWall(a []int, combi [][]int, level, height, index int, total *int64, pointer *[4][][]int) {
level++
var canCombine bool
for _, a1 := range combi {
canCombine = true
for _, value := range a {
if canCombine == false {
break
}
for _, value1 := range a1 {
if value == value1 {
canCombine = false
break
}
}
}
if canCombine == true && level < height {
if index%2 == 0 {
buildWall(a1, pointer[index+1], level, height, index+1, total, pointer)
} else {
buildWall(a1, pointer[index-1], level, height, index-1, total, pointer)
}
} else if level == height {
*total++
break
}
}
}
findCombinations works fine and returns a three dimensional array with all possible solutions. The arrays in [0] and [1] can (maybe) be put on top of each other without a crack occuring. Same for [2] and [3]. I choose to cut the array of all solutions up in 4 arrays by looking at the position of the first and last block used to build the wall as i assumed it would increase performance to loop over smaller arrays.
func findCombinations(width int) [4][][]int {
var i int
var tmp int
var tmpInt1 int
var tmpInt2 int
open := make([][]int, 0, 100)
var solutionsHolder [4][][]int
open = append(open, []int{3, 2})
tmpArray := make([]int, 0, 100)
for {
if len(open[i]) > 0 {
tmpArray = append(tmpArray[:i], open[i][0])
open[i] = append(open[i][:0], open[i][1:]...)
counter := 0
for _, x := range tmpArray {
counter += x
}
if counter == width {
solutionArray := make([]int, len(tmpArray)-1)
counter2 := 0
for n := 0; n < len(tmpArray)-1; n++ {
if n == 0 {
tmpInt1 = tmpArray[n] % 2
}
counter2 += tmpArray[n]
solutionArray[n] = counter2
}
tmpInt2 = counter2 % 2
if tmpInt1 == 0 && tmpInt2 == 0 {
solutionsHolder[0] = append(solutionsHolder[0], solutionArray)
} else if tmpInt1 == 1 && tmpInt2 == 1 {
solutionsHolder[1] = append(solutionsHolder[1], solutionArray)
} else if tmpInt1 == 1 && tmpInt2 == 0 {
solutionsHolder[2] = append(solutionsHolder[2], solutionArray)
} else {
solutionsHolder[3] = append(solutionsHolder[3], solutionArray)
}
for _, v := range open {
tmp += len(v)
}
if tmp == 0 {
return solutionsHolder
}
tmp = 0
} else if counter > width {
for _, v := range open {
tmp += len(v)
}
if tmp == 0 {
return solutionsHolder
}
tmp = 0
} else if counter < width {
i++
if len(open) <= i {
open = append(open, []int{3, 2})
} else {
open[i] = append(open[i], []int{3, 2}...)
}
}
} else {
i--
}
}
}
Its the wall function that calls a recursive function which will run for a very long time (i've had it run for an hour without a result) if you insert a width and height of wall(32,10) as they want you to compute on the website.
buildWall() which is called by wall checks whether there is no crack on the same position for two solutions and if this is the case it runs buildWall again for the next level of the wall until the walls height is reached. It does this for every solutions comparing it to all other possible solutions, though limited to one subset of the 3d array.
I'm thinking maybe there is another approach to find all the possible walls that can be combined, but i can't seem to wrap my head around it.

Related

How can I compare values in 2D array with values in 1D array in GoLang?

I need to compare 1D array's and 2D array's values and to return the result array which has similar values using Go:
func absolutePermutation(n int32, k int32) []int32 {
var position []int32
var i, j int32
var result []int32
for i = 1; i <= n; i++ {
position[i-1] = i
}
x := getPermutations(position)
resVal := permNum(n)
fmt.Println(x)
for i = 0; i < resVal; i++ {
for j = 0; j < 4; j++ {
fmt.Println(x[i][j])
**if int32(math.Abs(float64(position[(j*resVal)+i])-float64(x[i][j]))) == k** {
result[i] = x[i][j]
} else {
continue
}
}
}
return result
}
func getPermutations(elements []int32) [][]int32 {
permutations := [][]int32{}
if len(elements) == 1 {
permutations = [][]int32{elements}
return permutations
}
for i := range elements {
el := make([]int32, len(elements))
copy(el, elements)
for _, perm := range getPermutations(append(el[0:i], el[i+1:]...)) {
permutations = append(permutations, append([]int32{elements[i]}, perm...))
}
}
return permutations
}
func permNum (n int32) int32 {
if n == 0 {
return 1
}
return n * permNum(n-1)
}
I tried to create position (1D array into 2D array here.) but it didn't make sense.
As a newbie to GoLang, I get this error in this code which is written to get the permutation of a given number:
runtime error: index out of range [0] with length 0
I solved to some extent. you can refer to this.
func absolutePermutation(n int32, k int32) []int32 {
var buffer [1024 * 1024]int32
position := buffer[0:n]
result := make([]int32, n)
var i, j int32
for i = 1; i <= n; i++ {
position[i-1] = i
}
x := getPermutations(position)
for i = 0; i < permNum(n); i++ {
for j = 0; j < n; j++ {
if int32(math.Abs(float64(position[j])-float64(x[i][j]))) == k {
result[j] = x[i][j]
if j==n-1{
return result
}
}else{
break
}
}
}
result = nil
return result
}

Idiomatic Kotlin way to find an element to the right of a pivot that's just greater than the pivot

I would like to write a computer program such that given an array of numbers and a pivot index, it returns the index of the smallest element to the right of the pivot that is just greater than the pivot.
For example: if the input is [1, 4, 7, 2, 5, 6] and the pivot is at index 1 i.e. element 4, then the output should be 4 which is the index of 5 because 5 is the smallest element to the right of 4 that is greater than 4.
The following code works
fun justGreater(nums: IntArray, pivotIndex: Int): Int {
var result = 0
var currBest = Int.MAX_VALUE
for (i in pivotIndex until nums.size) {
if (nums[i] > nums[pivotIndex] && nums[i] < currBest) {
result = i
currBest = nums[i]
}
}
return result
}
I would like to write this idiomatically and succinctly.
You can try following:
fun justGreater(nums: IntArray, pivotIndex: Int): Int {
return nums.withIndex()
.sortedBy { it.value }
.first { it.index > pivotIndex && it.value > nums[pivotIndex] }
.index
}
Another option:
fun justGreater(nums: IntArray, pivotIndex: Int): Int {
return nums.mapIndexed { index, number -> index to number }
.sortedBy { (_, number) -> number }
.first { (index, i) -> index > pivotIndex && i > nums[pivotIndex] }
.first // returns pair, so we need to get only index
}
One more option:
fun justGreater(nums: IntArray, pivotIndex: Int): Int {
val filteredArr = nums.sliceArray(pivotIndex + 1 until nums.size)
.filter { it > nums[pivotIndex] }
return nums.indexOf(filteredArr.min() ?: -1) // we return -1 in case item was not found
}
Just a little improvement
fun IntArray.justGreater(pivotIndex: Int): Int {
var result = 0
var currBest = Int.MAX_VALUE
for (i in pivotIndex until size) {
if (get(i) > get(pivotIndex) && get(i) < currBest) {
result = i
currBest = get(i)
}
}
return result
}
I think there is no shortcut function to decrease code
This returns the smallest closest value position to the right of pivot:
fun justGreater(nums: IntArray, pivotIndex: Int): Int {
val least = nums.asList()
.subList(pivotIndex + 1, nums.size)
.filter { it > nums[pivotIndex] }
.min()!!
return nums.indexOf(least)
}

Insertion sort using Go

I'm having difficulty creating a random value insert in Go, I need to do 10 tests with 1000 numbers, then 10 tests with 5000 numbers, then 10 tests with 10000 numbers, then 10 tests with 15000 ... up to 50000
I made a code with function and another code without function and the 2 are wrong
package main
import (
"fmt"
"math/rand"
"time"
)
func main() {
var vetor [50000]int
for k := 1; k <= 10; {
k := (5 ^ k) * 1000
for i := 1000; i < 50000; {
vetor[i] = rand.Intn(1000)
fmt.Print(vetor[i], ",")
}
start := time.Now()
n := len(vetor)
if n < 2 {
return
}
for i := 1; i < n; i++ {
for j := i - 1; j >= 0; j-- {
if (vetor)[j] > (vetor)[j+1] {
(vetor)[j], (vetor)[j+1] = (vetor)[j+1], (vetor)[j]
} else {
break
}
}
}
t := time.Now()
decorrido := t.Sub(start)
}
}
package main
import (
"fmt"
"math/rand"
"time"
)
func insertion(array *[]int) {
n := len(*array)
if n < 2 {
return
}
for i := 1; i < n; i++ {
for j := i - 1; j >= 0; j-- {
if (*array)[j] > (*array)[j+1] {
(*array)[j], (*array)[j+1] = (*array)[j+1], (*array)[j]
} else {
break
}
}
}
}
func main() {
var vetor [50000]int
for k := 1; k <= 10; {
k := (5 ^ k) * 1000
for i := 1000; i < 50000; {
vetor[i] = rand.Intn(1000)
fmt.Print(vetor[i], ",")
}
start := time.Now()
insertion(&vetor)
t := time.Now()
decorrido := t.Sub(start)
}
}
I also need to calculate the run time for all the tests and take the averages out of all 10 results

Cell Compete Problems

Here is my assignment:
There is a colony of 8 cells arranged in a straight line where each day every cell competes with its adjacent cells(neighbour). Each day, for each cell, if its neighbours are both active or both inactive, the cell becomes inactive the next day,. otherwise itbecomes active the next day.
Assumptions: The two cells on the ends have single adjacent cell, so
the other adjacent cell can be assumsed to be always inactive. Even
after updating the cell state. consider its pervious state for
updating the state of other cells. Update the cell informationof
allcells simultaneously.
Write a fuction cellCompete which takes takes one 8 element array of
integers cells representing the current state of 8 cells and one
integer days representing te number of days to simulate. An integer
value of 1 represents an active cell and value of 0 represents an
inactive cell.
Program:
int* cellCompete(int* cells,int days)
{
//write your code here
}
//function signature ends
Test Case 1:
INPUT:
[1,0,0,0,0,1,0,0],1
EXPECTED RETURN VALUE:
[0,1,0,0,1,0,1,0]
Test Case 2:
INPUT:
[1,1,1,0,1,1,1,1,],2
EXPECTED RETURN VALUE:
[0,0,0,0,0,1,1,0]
This is the problem statement given above for the problem. The code which I have written for this problem is given below. But the output is coming same as the input.
#include<iostream>
using namespace std;
// signature function to solve the problem
int *cells(int *cells,int days)
{ int previous=0;
for(int i=0;i<days;i++)
{
if(i==0)
{
if(cells[i+1]==0)
{
previous=cells[i];
cells[i]=0;
}
else
{
cells[i]=0;
}
if(i==days-1)
{
if(cells[days-2]==0)
{
previous=cells[days-1];
cells[days-1]=0;
}
else
{
cells[days-1]=1;
}
}
if(previous==cells[i+1])
{
previous=cells[i];
cells[i]=0;
}
else
{
previous=cells[i];
cells[i]=1;
}
}
}
return cells;
}
int main()
{
int array[]={1,0,0,0,0,1,0,0};
int *result=cells(array,8);
for(int i=0;i<8;i++)
cout<<result[i];
}
I am not able to get the error and I think my logic is wrong. Can we apply dynamic programming here If we can then how?
private List<Integer> finalStates = new ArrayList<>();
public static void main(String[] args) {
// int arr[] = { 1, 0, 0, 0, 0, 1, 0, 0 };
// int days = 1;
EightHousePuzzle eightHousePuzzle = new EightHousePuzzle();
int arr[] = { 1, 1, 1, 0, 1, 1, 1, 1 };
int days = 2;
eightHousePuzzle.cellCompete(arr, days);
}
public List<Integer> cellCompete(int[] states, int days) {
List<Integer> currentCellStates = Arrays.stream(states).boxed().collect(Collectors.toList());
return getCellStateAfterNDays(currentCellStates, days);
}
private List<Integer> getCellStateAfterNDays(List<Integer> currentCellStates, int days) {
List<Integer> changedCellStates = new ArrayList<>();
int stateUnoccupied = 0;
if (days != 0) {
for (int i1 = 0; i1 < currentCellStates.size(); i1++) {
if (i1 == 0) {
changedCellStates.add(calculateCellState(stateUnoccupied, currentCellStates.get(i1 + 1)));
} else if (i1 == 7) {
changedCellStates.add(calculateCellState(currentCellStates.get(i1 - 1), stateUnoccupied));
} else {
changedCellStates
.add(calculateCellState(currentCellStates.get(i1 - 1), currentCellStates.get(i1 + 1)));
}
}
if (days == 1) {
System.out.println("days ==1 hit");
finalStates = new ArrayList<>(changedCellStates);
return finalStates;
}
days = days - 1;
System.out.println("Starting recurssion");
getCellStateAfterNDays(changedCellStates, days);
}
return finalStates;
}
private int calculateCellState(int previousLeft, int previousRight) {
if ((previousLeft == 0 && previousRight == 0) || (previousLeft == 1 && previousRight == 1)) {
// the state gets now changed to 0
return 0;
}
// the state gets now changed to 0
return 1;
}
Here is my solution in Java:
public class Colony
{
public static int[] cellCompete(int[] cells, int days)
{
int oldCell[]=new int[cells.length];
for (Integer i = 0; i < cells.length ; i++ ){
oldCell[i] = cells[i];
}
for (Integer k = 0; k < days ; k++ ){
for (Integer j = 1; j < oldCell.length - 1 ; j++ ){
if ((oldCell[j-1] == 1 && oldCell[j+1] == 1) || (oldCell[j-1] == 0 && oldCell[j+1] == 0)){
cells[j] = 0;
} else{
cells[j] = 1;
}
}
if (oldCell[1] == 0){
cells[0] = 0;
} else{
cells[0] = 1;
}
if (oldCell[6] == 0){
cells[7] = 0;
} else{
cells[7] = 1;
}
for (Integer i = 0; i < cells.length ; i++ ){
oldCell[i] = cells[i];
}
}
return cells;
}
}
Your program does not distinguish between the number of days to simulate and the number of cells.
#include <bits/stdc++.h>
using namespace std;
int* cellCompete(int* cells,int days)
{
for(int j=0; j<days; j++)
{
int copy_cells[10];
for(int i=1; i<9; i++)
copy_cells[i]=cells[i-1];
copy_cells[0]=0;copy_cells[9]=0;
for(int i=0; i<8; i++)
cells[i]=copy_cells[i]==copy_cells[i+2]?0:1;
}
return cells;
}
int main()
{
int arr[8]={1,1,1,0,1,1,1,1};
int arr2[8]={1,0,0,0,0,1,0,0};
cellCompete(arr2,1);
for(int i=0; i<8; i++)
{
cout<<arr2[i]<<" ";
}
}
Here's some sweet little python code:
def cell(arr, days):
new = arr[:] #get a copy of the array
n = len(arr)
if n == 1: print [0] #when only 1 node, return [0]
for _ in range(days):
new[0] = arr[1] #determine the edge nodes first
new[n - 1] = arr[n - 2]
for i in range(1, n-1):
new[i] = 1 - (arr[i-1] == arr[i+1]) #logic for the rest nodes
arr = new[:] #update the list for the next day
return new
arr = [1, 1, 1, 0, 1, 1, 1, 1]
days = 2
print cell(arr, days)
You can easily do this in Javascript with few lines of code
let cells = [1,1,1,0,1,1,1,1];
let numOfDays = 2;
let changeState = (cellarr)=> cellarr.map((cur, idx, arr)=> (arr[idx-1] ||0) + (arr[idx+1] || 0)===1?1:0);
let newCells =cells;
for (let i = 0 ; i <numOfDays; i++) newCells = changeState(newCells);
console.log(newCells);
This is a C# version of a possible answer. I really struggled with this for a while for some reason!
I also incorporated some of Janardan's stuff above as it helped spur me in the right direction. (cheers!)
The tricky part of the question was dealing with the fact that you had to persist the state of the cell to figure out the next cell competition which I had originally tried with a second array which was messy.
Note: I chose to use the Array.Copy method as I believe it is slightly more efficient and a lot more readable than copying arrays with a for loop when reading through.
Hopefully this helps someone out in the future!
public int[] cellCompete(int[] cell, int day)
{
//First create an array with an extra 2 cells (these represent the empty cells on either end)
int[] inputArray = new int[cell.Length + 2];
//Copy the cell array into the new input array leaving the value of the first and last indexes as zero (empty cells)
Array.Copy(cell, 0, inputArray, 1, cell.Length);
//This is cool I stole this from the guy above! (cheers mate), this decrements the day count while checking that we are still above zero.
while (day-- > 0)
{
int oldCellValue = 0;
//In this section we loop through the array starting at the first real cell and going to the last real cell
//(we are not including the empty cells at the ends which are always inactive/0)
for (int i = 1; i < inputArray.Length - 1; i++)
{
//if the cells below and above our current index are the same == then the target cell will be inactive/0
//otherwise if they are different then the target cell will be set to active/1
//NOTE: before we change the index value to active/inactive state we are saving the cells oldvalue to a variable so that
//we can use that to do the next "cell competition" comparison (this fulfills the requirement to update the values at the same time)
if (oldCellValue == inputArray[i + 1])
{
oldCellValue = inputArray[i];
inputArray[i] = 0;
}
else
{
oldCellValue = inputArray[i];
inputArray[i] = 1;
}
}
}
//Finally we create a new output array that doesn't include the empty cells on each end
//copy the input array to the output array and Bob's yer uncle ;)...(comments are lies)
int[] outputArray = new int[cell.Length];
Array.Copy(inputArray, 1, outputArray, 0, outputArray.Length);
return outputArray;
}
With C#
public static int[] cellCompete(int[] states, int days)
{
if (days == 0) return states;
int leftValue = 0;
int rigthValue = 0;
for (int i = 0; i < states.Length; i++)
{
if (i == states.Length - 1)
rigthValue = 0;
else
rigthValue = states[i + 1];
if (leftValue == rigthValue){
leftValue = states[i];
states[i] = 0;
}
else{
leftValue = states[i];
states[i] = 1;
}
}
cellCompete(states, days - 1);
return states;
}
I think some of the answers above could be more readable (in addition to being more efficient). Use an additional array and alternate updates between them depending on the number of days. You can return the most recently updated array, which will always be the correct one. Like this:
function cellCompete(states, days) {
const newStates = [];
let originalStates = true;
while (days--) {
changeStates(
originalStates ? states : newStates,
originalStates ? newStates : states,
states.length
);
originalStates = !originalStates;
}
return originalStates ? states : newStates;
}
function changeStates(states, newStates, len) {
newStates[0] = !states[1] ? 0 : 1;
newStates[len-1] = !states[len-2] ? 0 : 1;
for (let i = 1; i < len - 1; i++) {
newStates[i] = states[i-1] === states[i+1] ? 0 : 1;
}
}
Here is my solution in c++ using bitwise operators :
#include <iostream>
using namespace std;
void cellCompete( int *arr, int days )
{
int num = 0;
for( int i = 0; i < 8; i++ )
{
num = ( num << 1 ) | arr[i];
}
for( int i = 0; i < days; i++ )
{
num = num << 1;
num = ( ( ( num << 1 ) ^ ( num >> 1 ) ) >> 1 ) & 0xFF;
}
for( int i = 0; i < 8; i++ )
{
arr[i] = ( num >> 7 - i ) & 0x01;
}
}
int main()
{
int arr[8] = { 1, 0, 0, 0, 0, 1, 0, 0};
cellCompete( arr, 1 );
for(int i = 0; i < 8; i++)
{
cout << arr[i] << " ";
}
}
#include <stdio.h>
int main() {
int days,ind,arr[8],outer;
for(ind=0;ind<8;scanf("%d ",&arr[ind]),ind++); //Reading the array
scanf("%d",&days);
int dupArr[8];
for(outer=0;outer<days;outer++){ //Number of days to simulate
for(ind=0;ind<8;ind++){ //Traverse the whole array
//cells on the ends have single adjacent cell, so the other adjacent cell can be assumsed to be always inactive
if(ind==0){
if(arr[ind+1]==0)
dupArr[ind]=0;
else
dupArr[ind]=1;
}
else if(ind==7){
if(arr[ind-1]==0)
dupArr[ind]=0;
else
dupArr[ind]=1;
}
else{
if((arr[ind-1]==0&&arr[ind+1]==0) || (arr[ind-1]==1&&arr[ind+1]==1)){// if its neighbours are both active or both inactive, the cell becomes inactive the next day
dupArr[ind]=0;
}
else //otherwise it becomes active the next day
dupArr[ind]=1;
}
}
for(ind=0;ind<8;ind++){
arr[ind]=dupArr[ind]; //Copying the altered array to original array, so that we can alter it n number of times.
}
}
for(ind=0;ind<8;ind++)
printf("%d ",arr[ind]);//Displaying output
return 0;
}
Here is my code which i had created some months ago,
You want to create two different arrays, because altering same array element will gives you different results.
func competeCell(cell []uint, days uint) []uint{
n := len(cell)
temp := make([]uint, n)
for i :=0; i < n; i ++ {
temp[i] = cell[i]
}
for days > 0 {
temp[0] = 0 ^ cell[1]
temp[n-1] = 0 ^ cell[n-2]
for i := 1; i < n-2 +1; i++ {
temp[i] = cell[i-1] ^ cell[i +1]
}
for i:=0; i < n; i++ {
cell[i] = temp[i]
}
days -= 1
}
return cell
}
Using c++
#include <list>
#include <iterator>
#include <vector>
using namespace std;
vector<int> cellCompete(int* states, int days)
{
vector<int> result1;
int size=8;
int list[size];
int counter=1;
int i=0;
int temp;
for(int i=0;i<days;i++)//computes upto days
{
vector<int> result;
if(states[counter]==0)
{
temp=0;
list[i]=temp;
//states[i]=0;
result.push_back(temp);
}
else
{
temp=1;
list[i]=temp;
result.push_back(temp);
}
for(int j=1;j<size;j++)
{
if(j==size)
{
if(states[j-1]==0)
{
temp=0;
list[j]=temp;
//states[i]=1;
result.push_back(temp);
}
else
{
temp=1;
list[i]=temp;
//states[i]=1;
result.push_back(temp);
}
}
else if(states[j-1]==states[j+1])
{
temp=0;
list[j]=temp;
//states[i]=1;
result.push_back(temp);
}
else
{
temp=1;
list[j]=temp;
//states[i]=1;
result.push_back(temp);
}
}
result1=result;
for(int i=0;i<size;i++)
{
states[i]=list[i];
}
}
return result1;
}
Java solution
This is solution is Java, which will work any number of Cells and any number of days .
public class Solution
{
public List<Integer> cellCompete(int[] states, int days)
{
List<Integer> inputList = new ArrayList<Integer>();
List<Integer> finalList = new ArrayList<Integer>();
// Covert integer array as list
for (int i :states)
{
inputList.add(i);
}
// for loop for finding status after number of days.
for(int i=1; i<= days; i++)
{
if(i==1)
{
finalList = nextDayStatus(inputList);
}
else
{
finalList = nextDayStatus(finalList);
}
}
return finalList;
}
// find out status of next day, get return as list
public List<Integer> nextDayStatus(List<Integer> input)
{
List<Integer> output = new ArrayList<Integer>();
input.add(0,0);
input.add(0);
for(int i=0; i < input.size()-2; i++)
{
if (input.get(i) == input.get(i+2))
{
output.add(0);
}
else
{
output.add(1);
}
}
return output;
}
}
I know this has been answered, but I gave it a go in Java and am pretty sure it will work for any size states array along with number of days:
public class CellCompete {
public static List<Integer> cellCompete(int[] states, int days) {
List<Integer> resultList = new ArrayList<>();
int active = 1, inactive = 0;
int dayCount = 1;
// Execute for the given number of days
while (days > 0) {
int[] temp = new int[states.length];
System.out.print("Day " + dayCount + ": ");
// Iterate through the states array
for (int i = 0; i < states.length; i++) {
// Logic for first end cell
if (i == 0) {
temp[i] = states[i + 1] == active ? active : inactive;
resultList.add(temp[i]);
System.out.print(temp[i] + ", ");
}
// Logic for last end cell
if (i == states.length - 1) {
temp[i] = states[i - 1] == active ? active : inactive;
resultList.add(temp[i]);
System.out.println(temp[i]);
}
// Logic for the in between cells
if (i > 0 && i < states.length - 1) {
if ((states[i - 1] == active && states[i + 1] == active) || (states[i - 1] == inactive && states[i + 1] == inactive)) {
temp[i] = inactive;
} else {
temp[i] = active;
}
resultList.add(temp[i]);
System.out.print(temp[i] + ", ");
}
}
dayCount++;
days--;
// Reset the states array with the temp array
states = temp;
}
return resultList;
}
public static void main(String[] args) {
int[] states = {1, 1, 0, 1, 0, 1, 0, 0};
int days = 5;
// Total of 40
System.out.println(cellCompete(states, days) );
}
}
Where did the people who wanted optimized solutions go?
def Solution(states, days):
for i in range(days):
for j in range(len(states)):
if (j == 0):
states[i] = states[1]
elif (j == len(states)-1):
states[i] = states[-2]
else:
states[i] = abs(states[i-1] - states[i+1])
return states
By definition, all the cells, including non-existent ones, are in fact booleans:
var cellUpdate = (cells, days) => {
let result = [];
// update states
for(let i = 0; i < cells.length; i++) result.push((!Boolean(cells[i-1]) === !Boolean(cells[i+1])) ? 0 : 1) ;
// repeat for each day
if (days > 1) result = cellUpdate(result, days - 1);
return result;
Here is the best python Solution
value=input()
n=int(input())
lst=[]
for i in value:
if "1"in i:
lst.append(1)
elif "0" in i:
lst.append(0)
for _ in range(n):
store = []
for i in range(8):
if i==0:
store.append(lst[i+1])
elif i==7:
store.append(lst[i-1])
elif lst[i-1]==lst[i+1]:
store.append(0)
else:
store.append(1)
lst=store
print(store)
Scala solution:
def cellDayCompete(cells: Seq[Int]): Seq[Int] = {
val addEdges = 0 +: cells :+ 0
(addEdges.dropRight(2) zip addEdges.drop(2)).map {
case (left, right) =>
(left - right).abs
}
}
def cellCompete(cells: Seq[Int], days: Int): Seq[Int] = {
if (days == 0) {
cells
} else {
cellCompete(cellDayCompete(cells), days - 1)
}
}
A code run with the example above can be found at Scastie
Just answered this question today and here was my solution in python3
def cellCompete(states, days):
for i in range(0, days):
#this is where we will hold all the flipped states
newStates = []
'''
Algo: if neigbors are the same, append 0 to newStates
if they are different append 1 to newStates
'''
for currState in range(len(states)):
#left and right ptr's
left = currState - 1
right = currState + 1
#if at beginning of states, left is automatically inactive
if left < 0:
if states[right] == 1:
newStates.append(1)
else:
newStates.append(0)
#if at end of states, right is automatically inactive
elif right > 7: #we know there is always only 8 elems in the states list
if states[left] == 1:
newStates.append(1)
else
newStates.append(0)
#check to see if neighbors are same or different
elif states[left] != states[right]:
newStates.append(1)
else:
newStates.append(0)
#Set the states equal to the new flipped states and have it loop N times to get final output.
states = newStates
return states
def cellCompete(states, days):
d = 0
l = len(states)
while d < days:
new_states = [0] * l
for i in range(l):
if i == 0 and states[i+1] == 0 or i == l - 1 and states[i-1] == 0:
new_states[i] = 0
elif i == 0 and states[i+1] == 1 or i == l - 1 and states[i-1] == 1:
new_states[i] = 1
elif states[i+1] == states[i-1]:
new_states[i] = 0
else:
new_states[i] = 1
states = new_states
d = d + 1
return states
static int[] CellCompete(int[] states, int days)
{
int e = states.Length;
int[] newStates = new int[(e+2)];
newStates[0] = 0;
newStates[e+1] = 0;
Array.Copy(states, 0, newStates, 1, e);
for (int d = 0; d < days; d++)
{
states = Enumerable.Range(1, e).Select(x => newStates[x - 1] ^ newStates[x + 1]).ToArray();
newStates[0] = 0;
newStates[e + 1] = 0;
Array.Copy(states, 0, newStates, 1, e);
}
return states;
}
//Here is a working solution for this problem in C#
public class HousesinSeq
{
private string _result;
public string Result
{
get { return _result; }
}
public void HousesActivation(string houses, int noOfDays)
{
string[] housesArr = houses.Split(' ');
string[] resultArr = new string[housesArr.Length];
for (int i = 0; i < noOfDays; i++)
{
for (int j = 0; j < housesArr.Length; j++)
{
if (j == 0)
{
if (housesArr[j + 1] == "0")
{
resultArr[j] = "0";
}
else
{
resultArr[j] = "1";
}
}
else if (j == housesArr.Length - 1)
{
if (housesArr[j - 1] == "0")
{
resultArr[j] = "0";
}
else
{
resultArr[j] = "1";
}
}
else
{
if (housesArr[j + 1] == housesArr[j - 1])
{
resultArr[j] = "0";
}
else
{
resultArr[j] = "1";
}
}
}
resultArr.CopyTo(housesArr, 0);
}
foreach (var item in resultArr)
{
//Console.Write($"{item} ");
_result += item + " ";
}
_result = _result.Trim();
}
}
public class Colony {
public static int[] cellCompete(int[] cell, int day) {
int[] ar = new int[10];
for(int i=1; i<9; i++) {
ar[i] = cell[i-1];
}
while(day-- >0) {
int temp = 0;
for(int i=1; i<9; i++) {
if(Math.abs(temp-ar[i+1])==1) {
temp = ar[i];
ar[i] = 1;
}
else {
temp = ar[i];
ar[i] = 0;
}
}
}
return ar;
}
public static void main(String[] args) {
int[] cell = {1,0,1,1,0,1,0,1};
int day = 1;
cell = cellCompete(cell, day);
for(int i=1; i<9; i++) {
System.out.print(cell[i]+" ");
}
}
}

Add exactly 2 equal Elements to an array

I'm trying to add a random number (1...8) into an array.
I want to do this 16 times. The clue is, every number should only be in there twice. I got it working so far, but I don't think this is a clean way to do it. And the way I did it, it is not scaleable. If i wanted it to be, let's say for example 24 elements, and all of them 3 times, I'd have to rewrite all the code. Do You have an idea how to fix that? Thanks in advance!
var Numbers: [Int] = []
var randomNumber: Int = 0
let size: Int = 16
var index1 = 0
var index2 = 0
var index3 = 0
var index4 = 0
var index5 = 0
var index6 = 0
var index7 = 0
var index8 = 0
// Methods / Functions
func createRandomNumber() {
randomNumber = Int(arc4random() % 8 + 1)
}
func checkTwins() {
switch randomNumber {
case 1:
index1++
if index1 <= 2 {
Numbers.append(randomNumber)
}
else {
addRandomNumbertoArray()
}
case 2:
index2++
if index2 <= 2{
Numbers.append(randomNumber)
}
else {
addRandomNumbertoArray()
}
case 3:
index3++
if index3 <= 2 {
Numbers.append(randomNumber)
}
else {
addRandomNumbertoArray()
}
case 4:
index4++
if index4 <= 2 {
Numbers.append(randomNumber)
}
else {
addRandomNumbertoArray()
}
case 5:
index5++
if index5 <= 2 {
Numbers.append(randomNumber)
}
else {
addRandomNumbertoArray()
}
case 6:
index6++
if index6 <= 2 {
Numbers.append(randomNumber)
}
else {
addRandomNumbertoArray()
}
case 7:
index7++
if index7 <= 2 {
Numbers.append(randomNumber)
}
else {
addRandomNumbertoArray()
}
case 8:
index8++
if index8 <= 2 {
Numbers.append(randomNumber)
}
else {
addRandomNumbertoArray()
}
default: println("Generated Number out of Index")
}
}
func addRandomNumbertoArray() {
createRandomNumber()
checkTwins()
}
func fillUpArray() {
for _ in 1...size {
addRandomNumbertoArray()
}
}
// Calls
fillUpArray()
println(Numbers)
This was written in Swift Playground
What you can do is: First fill an array containing each of the
number 1, ..., 8 twice:
var array : [Int] = []
for i in 1 ... 8 {
array.extend(Repeat(count: 2, repeatedValue: i))
}
and then shuffle the array randomly:
array.shuffle()
where shuffle() is a Fisher-Yates shuffle.
A Swift implementation can be found in
How do I shuffle an array in Swift?:
extension Array {
mutating func shuffle() {
for i in 0..<(count - 1) {
let j = Int(arc4random_uniform(UInt32(count - i))) + i
swap(&self[i], &self[j])
}
}
}
This scales without problems to larger arrays and more repeated
elements.

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