腾讯马拉松-为什么时光不能倒流-hdu4510

#include<stdio.h>
int main()
{
  // freopen("1.txt","r",stdin);
    int n,h,m,s,h1,m1,s1;
    scanf("%d",&n);
    while(n--)
    {
        int h2=0,m2=0,s2=0;
        scanf("%d:%d:%d %d:%d:%d",&h,&m,&s,&h1,&m1,&s1);
        if(s>=s1)
            s2=s-s1;
        else
        {
            m--;
            s2=s-s1+60;

        }
        if(m>=m1)
            m2=m-m1;
        else
        {
            h--;
            m2=m-m1+60;
        }
        if(h>=h1)
            h2=h-h1;
        else
        {
            h2=h-h1;
            while(h2<0)
                h2+=12;
        }
        printf("%02d:%02d:%02d\n",h2,m2,s2);
    }
    return 0;
}