I've got a c study which it must print all the numbers in an array then how many times they repeated.
int lottery(int a,int b,int c,int d,int e,int f,int i,int count)
{
printf("Enter the loop count:");
scanf("%d",&d);
a=time(NULL);
srand(a);
int genel[100][100];
int hepsi[50]={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49};
count=0;
for(e=0;e<=d-1;e++)
{
for(b=0;b<=5;b++)
{
genel[e][b]=(rand()%49+1);
while(i>=0 && i<=49)
{
if(genel[e][b]==hepsi[i])
{
count=count+1;
}
else{
count=count;
}
}
printf("%d->%d\t",genel[e][b],count);
}
}
}
This doesnt work obviously. the output must be something like that
1-->0 2-->3 3-->15 etc
TY for your help, cheers :)
It is important that you understand what you are doing, naming is therefore very important. Nesting loops is okay if you know what you are doing. An easier to understand approach would be:
void lottery() {
int i, j //forloop counters
int randArray[100][100]; //array for random values
srand(Time(NULL)); //set random seed based on system time
//set random values
for(i = 0; i < 100; i++) {
for(j = 0; j < 100; j++) {
randArray[i][j] = rand()%49 + 1; //sets random ranging from 1 to 49 (49 incl)
}
}
//here you can start the counting procedure, which I won't spoil but ill give some hints below
}
There are a few options, first the easy lazy approach:
use a loop over all the values, 'int number' from 1 up to 49, inside that forloop use two forloops to search through the whole array, incrementing int x everytime you encounter the value 'number'. After youve searched through the whole array, you can use printf("%d -> %d", number, x); to print the value, set x to zero and count another number.
Another approach is as u tried,
create an array with for each number a location where you can increment a counter. Loop through the whole array now using two for-loops, increment the arraylocation corresponding to the value which youve found at randArray[i][j]. Afterwards print the array with counts using another forloop.
I suggest you try to clean up your code and approach, try again and come back with problems you encounter. Good luck!
sorry if this wasn't helpful to you, I tried to spoil not too much because according to my own experience programming should be learned by making mistakes.
Related
Task: Calculate the 25 values of the function y = ax'2 + bx + c on the interval [e, f], save them in the array Y and find the minimum and maximum values in this array.
#include <stdio.h>
#include <math.h>
int main()
{
float Y[25];
int i;
int x=3,a,b,c;
double y = a*pow(x,2)+b*x+c;
printf("a = ", b);
scanf("%d", &a);
printf("b = ", a);
scanf("%d", &b);
printf("c = ", c);
scanf("%d", &c);
for(i=0;i<25;i++)
{
printf("%f",y); //output results, not needed
x++;
}
system("pause");
}
Problems:
Cant understand how can I use "interval [e,f]" here
Cant understand how to save values to array using C libraries
Cant understand how to write/make a cycle, which will find the
minimum and maximum values
Finally, dont know what exactly i need to do to solve task
You must first ask the user for the values of a, b, c or initialize those variables, and ask for the interval values of e, f, or initialize those variables.
Now you must calculate double interval= (f - e)/25.0 so you have the interval.
Then you must have a loop for (int i=0, double x=e; i<25; i++, x += interval) and calculate each value of the function. You can choose to store the result in an array (declare one at the top) or print them directly.
Problems:
Cant understand how can I use "interval [e,f]" here
(f-e) / 25(interval steps)
Cant understand how to save values to array using C libraries
You need to use some form of loop to traverse the array and save the result of your calculation at every interval step. Something like this:
for(int i = 0; i < SIZE; i++)
// SIZE in this case 25, so you traverse from 0-24 since arrays start 0
Cant understand how to write/make a cycle, which will find the minimum and maximum values
For both cases:
traverse the array with some form of loop and check every item e.g. (again) something like this: for(int i = 0; i < SIZE; i++)
For min:
Initialize a double value(key) with the first element of your array
Loop through your array searching for elements smaller than your initial key value.
if your array at position i is smaller than key, save key = array[i];
For max:
Initialize a double value(key) with 0;
Loop through your array searching for elements bigger than your initial key value.
if your array at position i is bigger than key, save key = array[i];
Finally, dont know what exactly i need to do to solve task
Initialize your variables(yourself or through user input)
Create a function that calculates a*x^2 + b*x + c n times for every step of your interval.
Create a function for min & max that loops through your array and returns the smallest/biggest value.
Thats pretty much it. I will refrain from posting code(for now), since this looks like an assignment to me and I am confident that you can write the code with the information #Paul Ogilvie & I have provided yourself. Good Luck
#include<stdio.h>
#include<math.h>
int main()
{
double y[25];
double x,a,b,c,e,f;
int i,j=0;
printf("Enter a:",&a);
scanf("%lf",&a);
printf("Enter b:",&b);
scanf("%lf",&b);
printf("Enter c:",&c);
scanf("%lf",&c);
printf("Starting Range:",&e);
scanf("%lf",&e);
printf("Ending Range:",&f);
scanf("%lf",&f);
for(i=e;i<=f;i++)
{
y[j++]=(a*pow(i,2))+(b*i)+c;
}
printf("\nThe Maximum element in the given interval is %lf",y[j-1]);
printf("\nThe Minimum element in the given interval is %lf",y[0]);
}
Good LUCK!
I need to write code that sorts in 'n' run time and I don't know how to calculate it. I need to simply sort an array so that left side is odd and right side is even. This is what I wrote and I wonder how do I to find the run time.
for (i=0;i<size-1;i++)
{
if(ptr[i]%2==0 || ptr[i]==0)
{
for (j=i;j<size;j++)
{
if(ptr[j]%2!=0)
{
temp=ptr[i];
ptr[i]=ptr[j];
ptr[j]=temp;
break;
}
}
}
}
Thanks in advance.
Your runtime for this Code is O(N^2)
You can use Counting Sort to sort an array in linear time
For reference Counting Sort
As #VenuKant Sahu answered, OP's code is O(n*n)
That is due to its double nested for loops
for (i=0;i<size-1;i++)
...
for (j=i;j<size;j++)
...
I need to write code that sorts in 'n' run time
O(n) algorithm (did not want to just give the code)
The number of loop iterations below can not exceed n/2.
The increment even_side happens at most n times.
The decrement odd_side happens at most n times.
// set up indexes
int even_side = left-most valid index
int odd_side = right-most valid index
loop {
while (the_even_index_is_not_at_the_right_end && is_even(a[even_side]) increment even_side;
while (the_odd_index_is_not_at_the_left_end && !is_even(a[odd_side]) decrement odd_side
compare the indexes
if (done) exit the loop;
a[even_side] <==> a[odd_side]
}
Some helper code to set up a random array.
#define N 10
srand(time(NULL));
int a[N];
for (int i = 0; i<N; i++) {
a[i] = rand()%100;
printf(" %d", a[i]);
}
puts("");
I am doing a simple function that returns the minimum integer from numbers given from the user(array).
However, it always print 2686916 at the end. Here is my code:
int function()
{
int ar[100];
int i;
int smallest = INT_MAX;
int nums;
int num;
int sum=0;
printf("\nenter array size\n");
scanf("%d",&num);
for(i=0;i<num;i++)
{
scanf("%d",&ar[i]);
sum=sum+ar[i];
}
if (nums <smallest){
smallest=nums;
printf("the smallest %d\n,smallest);
return 0;
}
}
I'm not sure what I'm doing wrong.
My friend, it seems you are new to C, and before you ask questions like this one you should try to follow some tutorials for C. You might try something like this.
If the question you ask is not clear or the code you post won't compile anyway it is very hard to help you out. For now this is all I can do:
int function()
{
int ar[100];
int i;
int smallest = INT_MAX;
int nums = 0; //Always Initialize your variables!
int num = 0;
int sum= 0;
printf("\nenter array size\n");
scanf("%d",&num);
for(i=0;i<num;i++)
{
scanf("%d",&ar[i]);
sum=sum+ar[i];
}
if (nums <smallest)
{
smallest=nums;
printf("the smallest %d\n",smallest);
}
return 0; //Don't put this in a place that might not be executed!
}
Now it should at least compile, it still doesn't do anything useful as far as I can see. You compare "nums", a variable you didn't use before, with the biggest value of an int, set it to the never used "nums" and print it.
You might want use "sums" or "ar[i]" in the if statement instead, and printing one of these values.(still not 100% sure what you want to do).
Some tips for next time (before you ask a question!):
Variables should always be initialized
In your code you try to use the value of "nums" before it gets a value, this might cause errors or strange results in your code.
Don't put a return in a place that might be skipped,
In your code, "nums" would be bigger than "smallest" (unlikely, bit for example), the code would skip the if statement and never reach the return.
Read your compiler warnings
The code you posted can't compile, read your errors and warnings, and fix them.
(tip) Use better variable names, using names like nums, num and sum make it easy to overlook a mistake.
Recently I have gone through a problem like this
Write a program to read a sequence of N integers and print the number that
appears the maximum number of times in the sequence.
CONSTRAINTS
1 <= N <= 10000
The integers will be in the range [-100,100]
I have writen the following code:
main()
{int arr[201],max=0,maxelement,n,i,num;
int t;
scanf("%d",&n);
int *storenum=(int *)malloc(sizeof(int)*n);
for(i=0;i<201;i++)
{
arr[i]=0;
}
for(i=0;i<n;i++)
{
scanf("%d",&num);
storenum[i]=num;
if(num<=100 && num>=-100)
{
arr[num+100]=arr[num+100]+1;
}
}
for(i=0;i<n;i++)
{
int t=storenum[i]+100;
if(arr[t]>max)
{ maxelement=storenum[i];
max=arr[t];}
}
printf("\n\n%d",maxelement);
getch();
}
Now I think this code is not optimized one...I want to have a solution that would have less time and space complexity and better solution.
You don't have to iterate through all N items a second time, just iterate through the 201 counts looking for the largest.
Your code looks very close to optimal. It can be made only a little better given your constraints.
Use memset when you mean memset. Yes the compiler will pick it up 99% of the time, but why bother?
for(i=0;i<201;i++) arr[i]=0; // becomes
memset(arr, '\0', sizeof(arr))
The count for any given item can be no larger than 10000. That means it can be held in a ushort!
int arr[201]; // becomes
uint16_t arr[201];
Your second loop should go from for(i = -100; i <= 100; i++) instead, and just loop over arr.
Your code is butt-ugly. Use a consistent indentation, brace style, and don't cram 50 declarations on the same line. Spaces are okay between elements. arr should probably be named something meaningful, I like counts. It kind of looks like you're trying to use gnu style C, but K&R works too, really just pick any style guide and glance through it.
I am (re-)learning C and in the book I am following we are covering arrays, and the book gives an algorithm for finding the first n primes; myself being a mathematician and a decently skilled programmer in a few languages I decided to use a different algorithm (using the sieve of Eratosthenes) to get the first n primes. Well making the algorithm went well, what I have works, and even for moderately large inputs, i.e. the first 50,000 primes take a bit to run as you would expect, but no issues. However when you get to say 80,000 primes pretty much as soon as it begins a window pops up saying the program is not responding and will need to quit, I made sure to make the variables that take on the primes were unsigned long long int, so I should still be in the acceptable range for their values. I did some cursory browsing online and other people that had issues with large inputs received the recommendation to create the variables outside of main, to make them global variables. I tried this for some of the variables that I could immediately put outside, but that didn't fix the issue. Possibly I need to put my arrays isPrime or primes outside of main as well? But I couldn't really see how to do that since all of my work is in main.
I realize I should have done this with separate functions, but I was just writing it as I went, but if I moved everything into separate functions, my arrays still wouldn't be global, so I wasn't sure how to fix this issue.
I tried making them either static or extern, to try and get them out of the stack memory, but naturally that didn't work since they arrays change size depending on input, and change over time.
the code is:
#include <math.h>
#include <stdbool.h>
#include <stdio.h>
unsigned long long int i,j;
unsigned long long int numPrimes,numPlaces;
int main(void)
{
bool DEBUG=false;
printf("How many primes would you like to generate? ");
scanf("%llu",&numPrimes);
// the nth prime is bounded by n*ln(n)+n*ln(ln(n)), for n >=6
// so we need to check that far out for the nth prime
if (numPrimes>= 6)
numPlaces = (int) numPrimes*log(numPrimes)+
numPrimes*log(log(numPrimes));
else
numPlaces = numPrimes*numPrimes;
if(DEBUG)
printf("numPlaces: %llu\n\n", numPlaces);
// we will need to check each of these for being prime
// add one so that we can just ignore starting at 0
bool isPrime[numPlaces+1];
// only need numPrimes places, since that is all we are looking for
// but numbers can and will get large
unsigned long long int primes[numPrimes];
for (i=2; i<numPlaces+1;i++)
isPrime[i] = true; // everything is prime until it isn't
i=2; // represents current prime
while (i < numPlaces + 1)
{
for (j=i+1;j<numPlaces+1;j++)
{
if (isPrime[j] && j%i ==0) // only need to check if we haven't already
{
isPrime[j] = false;// j is divisibly by i, so not prime
if(DEBUG)
{
printf("j that is not prime: %llu\n",j);
printf("i that eliminated it: %llu\n\n",i);
}//DEBUG if
}//if
}//for
// ruled out everything that was divisible by i, need to choose
// the next i now.
for (j=i+1;j<numPlaces+2;j++)// here j is just a counter
{
if (j == numPlaces +1)// this is to break out of while
{
i = j;
break;
}// if j = numPlaces+1 then we are done
else if (isPrime[j]==true)
{
i = j;
if (DEBUG)
{
printf("next prime: %llu\n\n",i);
}//DEBUG if
break;
}//else if
}// for to decide i
}//while
// now we have which are prime and which are not, now to just get
// the first numPrimes of them.
primes[0]=2;
for (i=1;i<numPrimes;i++)// i is now a counter
{
// need to determine what the ith prime is, i.e. the ith true
// entry in isPrime, 2 is taken care of
// first we determine the starting value for j
// the idea here is we only need to check odd numbers of being
// prime after two, so I don't need to check everything
if (i<3)
j=3;
else if (i % 2 ==0)
j = i+1;
else
j = i;
for (;j<numPlaces+1;j+=2)// only need to consider odd nums
{
// check for primality, but we don't care if we already knew
// it was prime
if (isPrime[j] && j>primes[i-1])
{
primes[i]=j;
break;
}//if, determined the ith prime
}//for to find the ith prime
}//for to fill in primes
// at this point we have all the primes in 'primes' and now we just
// need to print them
printf(" n\t\t prime\n");
printf("___\t\t_______\n");
for(i=0;i<numPrimes;i++)
{
printf("%llu\t\t%llu\n",i+1,primes[i]);
}//for
return 0;
}//main
I suppose I could just avoid the primes array and just use the index of isPrime, if that would help? Any ideas would help thanks!
Your problem is here, in the definition of the VLA ("Variable Length Array", not "Very Large Array")
bool isPrime[numPlaces+1];
The program does not have enough space in the area for local variables for the array isPrime when numPlaces is large.
You have two options:
declare the array with a "big enough" size outside of the main function and ignore the extra space
use another area for storing the array with malloc() and friends
option 1
#include <stdio.h>
unsigned long long int i,j;
bool isPrime[5000000]; /* waste memory */
int main(void)
option 2
int main(void)
{
bool *isPrime;
// ...
printf("How many primes would you like to generate? ");
scanf("%llu",&numPrimes);
// ...
// we will need to check each of these for being prime
// add one so that we can just ignore starting at 0
isPrime = malloc(numPrimes * sizeof *isPrime);
// ... use the pointer exactly as if it was an array
// ... with the same syntax as you already have
free(isPrime);
return 0;
}
The array you allocate is a stack variable (by all likelihood), and stack size is limited, so you are probably overwriting something important as soon as you hit a certain size threshold, causing the program to crash. Try using a dynamic array, allocated with malloc, to store the sieve.