UVA 11650 - Mirror Clock

Problem link

Keyword: ad hoc

Algorithm:

It can be solved using time subtraction. Only remember that you should print 12:30 instead of 0:30.

Code:

#include<cstdio>

int main()
{
    int t, h, m, ans;
    scanf( "%d", &t );

    while( t-- )
    {
        scanf( "%d:%d", &h, &m );
        ans = 720 - 60 * h - m;
        if( ans < 60 )
            ans += 720;
        printf( "%02d:%02d\n", ans / 60, ans % 60 );
    }

    return 0;
}