HDU 4510 小Q系列故事——為什麼時光不能倒流

這道題很水的，記得ACM剛入門的時候，做過類似的題目，相當於加減法的類比

代碼：

#include <cstdio>int HH, MM, SS, hh, mm, ss, T;int main ( ) {    scanf ( "%d", &T );        while ( T-- ) {            scanf ( "%d:%d:%d", &HH, &MM, &SS );            scanf ( "%d:%d:%d", &hh, &mm, &ss );            if ( SS >= ss ) SS -= ss;            else {                MM--;                SS = (SS + 60 - ss);            }            if ( MM >= mm ) MM -= mm;            else {                H--;                MM = MM + 60 - mm;            }            if ( HH >= hh ) HH -= hh;            else {                HH = HH - hh + 12;            }    HH %= 12;    HH = (HH+12)%12;            printf ( "%.2d:%.2d:%.2d\n", HH, MM, SS );        }}