URAL 1032 A - Find a Multiple——抽屉原理+构造

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
const int maxn = 2 * 1e4 + 10;

int n, a[maxn], dp[maxn], vis[maxn];

int main() {
    while (~scanf("%d", &n)) {
        if (n == 0) {
            printf("0\n"); continue;
        }
        memset(vis, 0, sizeof(vis));
        for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
        dp[1] = a[1];
        if (dp[1] % n == 0) {
            printf("%d\n%d\n", 1, a[1]);
            continue;
        }
        vis[dp[1] %  n] = 1;
        bool ok = false;
        for (int i = 2; i <= n; i++) {
            dp[i] = dp[i - 1] + a[i];
            if (dp[i] % n == 0) {
                ok = true;
                printf("%d\n", i);
                for (int j = 1; j <= i; j++) printf("%d\n", a[j]);
                break;
            }
            else if (vis[dp[i] % n]) {
                ok = true;
                printf("%d\n", i - vis[dp[i] % n]);
                for (int j = vis[dp[i] % n] + 1; j <= i; j++) printf("%d\n", a[j]);
                break;
            }
            vis[dp[i] % n] = i;
        }
        if (!ok) printf("%d\n", 0);
    }
    return 0;
}