【思维】E. Special Elements

Codeforces Round 640 (Div. 4)
E. Special Elements

题意：给定元素个数<=8000且元素大小<=8000的数组，问其中可表示为连续子序列的和的元素有多少个

思路：前缀和算出所有连续子序列的和，拿桶数组装着，注意和>8000的就不要装了，没必要并且会越界

#include<iostream>
#include<cstring>
#include<algorithm>
#include<cstring>
using namespace std;
int a[8000 + 10];
int b[8000 + 10];
int vis[8000+10];
int main()
{
	int t;
	cin >> t;
	while (t--) {
		for (int i = 0; i <= 8000 + 5; i++) vis[i] = 0;
		int n;
		cin >> n;
		for (int i = 1; i <= n; i++) {
			cin >> a[i];
			b[i] = b[i - 1] + a[i];
		}
		for (int l = 1; l < n; l++) {
			for (int r = l + 1; r <= n; r++) {
				int sum = b[r] - b[l - 1];
				if(sum<=n) vis[sum]++;
			}
		}
		int ans = 0;
		for (int i = 1; i <= n; i++) if (vis[a[i]]) ans++;
		cout << ans << endl;
	}
	return 0;
}