3n+1 problem

[nick2]

i think i ve solved it, it gives me correct answers, but when i try to submit, it says wrong answer.

is there something wrong with my code?

#include <stdio.h>
int main() {
    unsigned long i,x,y,k,max,s,temp;
    while (scanf("%lu %lu",&x,&y)!=EOF){
          if (x>y){
                   temp=y;
                   y=x;
                   x=temp;
                   }
         max=1;
        for (i=x;i<=y;i++){
            s=function(i,1);
            if (s>max){
                          max=s;
            }
            }
            printf("%lu %lu %lu",x,y,max);
            }
            return 0;
}
function(unsigned long n, unsigned long m) {
    while (n!=1){
              if (n%2==1){
                          n=n*3+1;
                          m++;
                          }
              else {
                   n=n/2;
                   m++;
                   }
                   }
     return m;
                         }

thanks

[laserlight]

You might want to make your indentation somewhat more consistent, and using whitespace to make your code more readable:

#include <stdio.h>

unsigned long function(unsigned long n, unsigned long m);

int main() {
    unsigned long i, x, y, max, s, temp;
    while (scanf("%lu %lu", &x, &y) != EOF) {
        if (x > y) {
            temp = y;
            y = x;
            x = temp;
        }

        max = 1;
        for (i = x; i <= y; i++) {
            s = function(i, 1);
            if (s > max) {
                max = s;
            }
        }

        printf("%lu %lu %lu", x, y, max);
    }
    return 0;
}

unsigned long function(unsigned long n, unsigned long m) {
    while (n != 1) {
        if (n % 2 == 1) {
            n = n * 3 + 1;
            m++;
        }
        else {
            n = n / 2;
            m++;
        }
    }
    return m;
}

Notice that I have given function an explicit return type of unsigned long (otherwise it would have a default return type of int) and used a function prototype. I have also removed the variable k since it was not used.

[nick2]

thanks, but again it says wrong answer :/

i think there is something missing but dont know what it is

ps: im talking about uva online judge.

[laserlight]

Well, at least you have eliminated the possibility of an incorrect range. Now, double check if the format of output produced by your program matches the required format.

[nick2]

well i found out what it actually was

if we have input like
1 10

it should print out
1 10 20

and if we have input like

10 1

it should be

10 1 20

but the problem is that i printed the first two numbers at the end, after actually changing their value by using the variable temp.

so the correct is:

#include <stdio.h>

unsigned long function(unsigned long n, unsigned long m);

int main() {
    unsigned long i, x, y, max, s, temp;
    while (scanf("%lu %lu", &x, &y) != EOF) {
          printf("%lu %lu",x,y);
        if (x > y) {
            temp = y;
            y = x;
            x = temp;
        }

        max = 1;
        for (i = x; i <= y; i++) {
            s = function(i, 1);
            if (s > max) {
                max = s;
            }
        }

        printf(" %lu\n",max);
    }
    return 0;
}

unsigned long function(unsigned long n, unsigned long m) {
    while (n != 1) {
        if (n % 2 == 1) {
            n = n * 3 + 1;
        }
        else {
            n = n / 2;
        }
m++;
    }
    return m;
}

thank you very much laserlight for you help and time.