改为 <=实际上代码可以很简单
#include "stdio.h" int main() { int N, A, B; scanf("%d%d%d", &N, &A, &B); A -= (N - 1) % A + 1; B -= (N - 1) % B + 1; if (A < B) printf("%d", A); else printf("%d", B); }