Find a multiple POJ - 2356 （抽屉原理）

#include<cstdio>
#include<cstring>

const int maxn = 1e5 + 5;
int num[maxn], hash[maxn], sum[maxn];
int n;

int main()
{
    while (scanf("%d", &n) != EOF){
        memset(hash, 0, sizeof(hash));
        for (int i = 1; i <= n; ++i)
            scanf("%d", &num[i]);

        int t = 1, s = 1;
        for (int i = 1; i <= n; ++i)
        {
            sum[i] = (sum[i - 1] + num[i]) % n;
            if (sum[i] == 0){
                t = i;
                break;
            }
            if (hash[sum[i]] > 0){
                s = hash[sum[i]] + 1;
                t = i;
                break;
            }
            hash[sum[i]] = i;
        }
        printf("%d\n", t - s + 1);
        for (int i = s; i <= t; ++i)
            printf("%d\n", num[i]);
    }
}