There are a list of cards with two numbers on it, one on the front and one on the back. I need to maximize the bitwise-and (&) by either taking the front or back of each card. And yes it should be done in minimum flips possible, as initially the cards are facing front and when I pick the number at the back, I am making a flip. I have solved this problem using the following code:
for(int bit = 1<<30;bit > 0;bit>>=1){
bool possible = true;
//Setting state to '0' for not flipping and '1' for flipping.'-1' means unset
for(int i = 0;i < n;i++){
if(state[i]==0 && !(A[i]&bit))possible = false;//A is the array to store front value
else if(state[i]==1 && !(B[i]&bit))possible = false;// B is the array to store back value
else if(!(A[i]&bit) &&!(B[i]&bit))possible = false;
}
if(!possible)continue;
for(int i = 0;i < n;++i){**//SNIPPET TO REPLACE START**
if (state[i] != -1)continue;
if (!(A[i]&bit))state[i] = 1;
else if (!(B[i]&bit))state[i] = 0;//SNIPPET TO REPLACE END
}
/*USING THIS SNIPPET GIVED WRONG ANSWER
for(int i = 0;i < n;++i){
if(state[i]!=-1)continue;
if(A[i] & bit)state[i]=0;
else if(B[i] & bit)state[i]=1;
}
*/
}
int ans;
int count_ = 0;
ans = (1 << 30) - 1;
for(int i = 0;i < n;i++){
if(state[i]==1){
ans&=B[i];
count_++;
}
else ans&=A[i];
}
As explained in the comments of the code, I feel the both snippet should work just fine. I maybe missing some edge case why the snippet I commented does not work as the one I actually used in the code for execution.
Related
else {
masterNum[3] = guess % 10; //checks integers in their respective positions
masterNum[2] = ((guess - guess%10)/10)%10;
masterNum[1] = ((guess - guess % 100)/100)%10;
masterNum[0] = (guess - guess % 1000)/1000;
masterDigit(guess, masterNum);
}
//}
//This method determines the total number of correct digits but not
//necessarily in the correct position
public static int masterDigit (int [] guess,int [] code) //int [] guess
{
int i,j,k,number;
int [] tempGuess = new int [4]; //an array to hold a copy of a code
boolean found;
number = 0;
for(k=0; k<4; k++) //copies code to tempGuess so code
//doesn't get changed (you can't just assign code to tempGuess)
tempGuess[k] = code[k];
for(i = 0; i < 4; i++)
{
j=0;
found = false;
while(j < 4 && found == false) // a while loop instead of a
// for loop so duplicates are only counted once
{
if(guess[i] == tempGuess[j])
{
found = true;
tempGuess[j] = -1; // fills up tempGuess with an impossible
// value so that index only gets
// counted once
number++;
}
j++;
}
}
return number;
}
This code is for a Mastermind game with integers. Upon running through the compiler, there is an error saying that integer "guess" cannot be converted to an array. How can I get my guess (defined as an integer scanner console) to go into this method that will check which numbers are correct?
I need help with figuring out what exactly is this error and why is it occuring. When I debud the program everything seems to be working perfectly fine! I do not get this.
Code:
void WordsRandom()
{
srand((unsigned)time(NULL));
n = rand() % 10;
checkRandom[k] = n; //ERROR HERE --> THREAD 1: EXC_BAD_ACCESS
k ++; //k is set to 0 originally
rowRandom = getRandomNumber();
colRandom = getRandomNumber();
}
I do not know why this is happening. As far as I know, in this case there is no need to use the %d specifier right? I f you require further code just let me know.
WordsRandom is being called by other methods:
void horizontalOrientation()
{
size = (int)strlen(words[n]);
if((colRandom + (size - 1)) <= 9)
{
for(int j = 0; j < (strlen(words[n])); j ++)
{
puzzle[rowRandom][colRandom] = words[n][j];
colRandom ++;
}
}
else
{
do
{
WordsRandom();
horizontalOrientation();
}while((colRandom + (size - 1)) > 9);
}
}
I have other functions similiar to this for vertical and diagonal orientation.
Two things are troublesome here:
I do not see declarations for either the size of your array (checkRandom[]) or the integer value that you're using to index it (k). If you're receiving an access error, then chances are that you're indexing past the boundaries of your array into memory that isn't yours.
I'd try refactoring your code so that you can check you aren't passing the maximum index of your array (size -1)
I am trying to create an array and be able to compare the second to last and last item in an array. It needs to be constantly adding and comparing to work correctly. This is just a function I am trying to get running to help control a stepper motor function. I have a loop that is going to fast for me to be able to compare directly. I do know that some of it is wrong but as I haven't coded in C very much I can't figure out how to use an array correctly. Thank you in advance.
int P[10],V[10],i,x,y;
Serial.print("checkvalue = ");
Serial.print(checkvalue);Serial.print("\n");
Serial.print("P = "); Serial.print(P[i]); Serial.print("\n"); //attempting to print array
Serial.print("V = "); Serial.print(V[i]); Serial.print("\n"); //to see if it is collecting
//data correctly
//these variables are declared above in my code, just didn't copy in
Dgreadpb = digitalRead(13);
PBcheck = Dgreadpb;
//Serial.print("Button in = ");Serial.print(Dgreadpb); Serial.print("\n");
Dgreadvls = digitalRead(12);
VLScheck = Dgreadvls;
//Serial.print("Photo in = ");Serial.print(Dgreadvls); Serial.print("\n");
for (i = 0; i < 10; i++){
x = Dgreadpb;
y = Dgreadvls;
P[i] = x;
V[i] = y;
if (P[i-1] == P[i] && V[i-1] == V[i]){ //trying to compare second to
checkvalue == 0; //last term to the last term
return;
}
else if(P[i-1] != P[i] || V[i-1] != V[i]){
checkvalue == 1;
return;
}
}
delay (1000);
By "trying to compare second to last term to the last term", do you mean "Trying to compare second to last term with their previous"? If that's the case your indices are wrong, it should be for(i = 1; i<10; i++).
Also both conditions are opposite (Either both are equal or AT LEAST one of them is different), there is no need for else if. Even more, cause both conditions are opposite it will never complete the loop. I think that's not the intention, if you're trying to say that only one of them are different you should do:
if (P[i-1] == P[i] && V[i-1] == V[i]){ //If both are equal
checkvalue == 0;
return;
}
else if(P[i-1] == P[i] || V[i-1] == V[i]){ //If only one is equal
checkvalue == 1;
return;
}
Ok, then I'd make a different thing.
Looking at your comment, it looks like you want to do something like this: read the value of two pins, compare them to the last value you read and, if they are differernt, start the motor, otherwise stop it.
Now, a lot of info are missing (e.g. how do you check the motor? how often do you want to check the sensor? what sensor?) but IMHO you should do something like this.
In this code I suppose that
you want to check the sensor every 100 milliseconds
if the values differ, you want to turn on the motor for the next 100 ms
the motor is a DC motor turned on by setting the corresponding pin (e.g. 10)
the sensors have a binary output on pins 12 and 13, since you wrote that in the code
BTW I used the millis() function because I hate the delay, since it blocks the uC. Using my function you'll be able to perform other operations while it is idle.
const byte motorPin = 10;
const byte sensorPPin = 12;
const byte sensorVPin = 13;
#define LOOP_TIME_MS 100
unsigned long lastLoopTime;
boolean lastPval, lastVval;
void setup()
{
pinMode(motorPin, OUTPUT);
pinMode(sensorPPin, INPUT);
pinMode(sensorVPin, INPUT);
lastPval = digitalRead(sensorPPin);
lastVval = digitalRead(sensorVPin);
lastLoopTime = millis();
}
void loop()
{
if ((millis() - lastLoopTime >= LOOP_TIME_MS)
{
boolean Pval = digitalRead(sensorPPin);
boolean Vval = digitalRead(sensorVPin);
if ((Pval != lastPval) || (Vval != lastVval))
{
digitalWrite(motorPin, HIGH);
}
else
{
digitalWrite(motorPin, LOW);
}
lastLoopTime += LOOP_TIME_MS;
}
/* Here you can do something else */
}
EDIT: If, on the other side, you want to use arrays (because you want to test the last N values instead of just the previous one) please provide further info on what are the changing conditions (or better provide examples)
I'm writing a program that will read input and then give back a histogram of the character count from K & R - Ex. 1.13
Any suggestions on how I can improve my code? Does it matter whether or not if I test for status in condition or out first? I have noticed in my examples people test to see if c is a blank or tab first.
I think I need to revisit my histogram. It doesn't really scale the results. It just draws a hyphen based on the length.
Revised to make a little bit more readable I think.
// Print a histogram of the length of words in it's input.
#include <stdio.h>
#define IN 1
#define OUT 2
#define MAX 99
int main(){
int c; // the character
int countOfLetters = 0;
int insideWord = OUT;
int frequencyOfLengths[MAX];
int longestWordCount = 0;
int i, j; // Counters
for (i = 0; i < MAX; i++){
frequencyOfLengths[i] = 0;
}
while ((c = getchar()) != EOF){
if (c == ' ' || c == '\n' || c == '\t'){
if (insideWord == IN){
if (countOfLetters > MAX){
return 1;
}
++frequencyOfLengths[countOfLetters];
if (countOfLetters >= longestWordCount) longestWordCount = countOfLetters;
}
countOfLetters = 0;
}
else {
countOfLetters++;
insideWord = IN;
}
}
for (i = 1; i <= longestWordCount; i++){
printf("%3i : %3i ", i, frequencyOfLengths[i]);
for (j = 0; j < frequencyOfLengths[i]; j++){
printf("*");
}
printf("\n");
}
return 0;
}
Definitely scale results, check out my Character Histogram that does a horizontal scaling histogram.
Also, you could benefit a y-axis label. It's hard to tell which bar is for which kind of word length. I have no idea which bar is for what word length.
I added this code right before you display the histogram, it basically halves every value, which does throw off your bar number labels. You can figure it out!
// Iterates and tells us the most frequent word length
int mostFrequent = 0;
for (i = 1; i < MAXWORD; i++)
if (charCount[i] > mostFrequent)
mostFrequent = charCount[i];
// If the bar will be too big, cut every value in half
while (mostFrequent > 60) {
for (i = 1; i < MAXWORD; i++)
if (charCount[i] > 0) {
charCount[i] /= 2;
charCount[i] |= 1;
}
// Check again to find the most frequent word length category
mostFrequent = 0;
for (i = 1; i < MAXWORD; i++)
if (charCount[i] > mostFrequent)
mostFrequent = charCount[i];
}
Honestly the bars are hard to read, maybe just use a single row of characters such as █ !
Great book so far, we're practically reading it together and are on the same page!
Cheers
/edit: thanks for the help so far, however I haven't got any of the solutions to take the sample input and give the sample output. My description isn't the clearest, sorry.
I have an array composed of binary data. What I want to do is determine how long each unbroken segment of 1s or 0s is.
Say I have this data:
0111010001110
In an array binaryArray which I need to translate to:
0100110
stored in nwArray where 0 represents a narrow (less than 3 digits long) and 1 represents wide (>3 digits long). I am not concerned with the binary value but with the length of each component. I'm not sure if that explanation makes sense.
This is what I have; it doesn't work, I can see why, but I can't think of a good solution.
for(x=0;x<1000;x++){
if(binaryArray[x]==binaryArray[x+1]){
count++;
if(count>=3){
nwArray[y]=1;
y++;
count=0;
}
}else{
if(barcodeArray[x]){
nwArray[y]=0;
}
}
}
Does this do it?
int count = 0;
for (x=0; x<1000;x++)
{
if (binaryArray[x] != binaryArray[x+1])
{
if (count < 3)
nwArray[y]=0;
else
nwArray[y]=1;
y++;
count = 0;
}
else
count++;
}
One problem you have is that you compare count with 3 too early. Wait until you see a change in the bitstream. Try a while loop until the bit flips then compare the count.
Modified #MikeW's answer:
int count = 0;
int nwSize = 0;
const int ilast = SIZEOF(binaryArray) - 1;
for (int i = 0; i <= ilast; ++i)
if (i == ilast || binaryArray[i] != binaryArray[i+1]) {
nwArray[nwSize++] = (count > 1); /* true for '1110'; false for '110' */
count = 0;
}
else
++count;
assert(count == 0);