View Code of Problem 56

#include <stdio.h>

typedef struct tm{
    int hour,munite,second;
}tm;

int comp(const void* a,const void* b)
{
    tm* c = (tm*)a;
    tm* d = (tm*)b;
    if(c->hour == d->hour)
    {
        if(c->munite == d->munite)
            return d->second - c->second;
        else
            return d->munite - c->munite;
    }
    else
        return d->hour - c->hour;
}

int main(void)
{
    tm a[2];
    int i;
    for(i = 0;i < 2;i++)
    {
        scanf("%d:%d:%d",&a[i].hour,&a[i].munite,&a[i].second);
    }
    qsort(a,2,sizeof(tm),comp);
    int s,m,h;
    s = a[0].second - a[1].second;
    if(h < 0)
    {
        s += 60;
        a[0].munite--;
    }
    m = a[0].munite - a[1].munite;
    if(m < 0)
    {
        m += 60;
        a[0].hour--;
    }
    h = a[0].hour - a[1].hour;
    if(m < 10 && s < 10)
        printf("%d:0%d:0%d\n",h,m,s);
    else if(m < 10 && s >= 10)
        printf("%d:0%d:%d\n",h,m,s);
    else if(m >= 10 && s < 10)
        printf("%d:%d:0%d\n",h,m,s);
    else
        printf("%d:%d:%d\n",h,m,s);
    return 0;
}