1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
#include <bits/stdc++.h>
#define int long long
using namespace std;
int n, cnt;
long long res;
int tab[505];
int pre[505];
int ntab[125255];
int values[500*20000][2];
int32_t main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cin >> n;
    for (int i = 1; i <= n; ++i)
    {
        cin >> tab[i];
        pre[i] = pre[i-1] + tab[i];
    }
    for (int i = 1; i <= n; ++i)
    {
        for (int j = i; j <= n; ++j)
        {
            ntab[cnt] = (pre[j] - pre[i-1]);
            ++cnt;
        }
    }
    for (int i = 0; i < cnt; ++i)
    {
        for (int j = i+1; j < cnt; ++j)
        {
            if (ntab[i] + ntab[j] > 0)
            {
                res += values[ntab[i] + ntab[j]][0];
            }
            else
            {
                res += values[-ntab[i] - ntab[j]][1];
            }
        }
        if (ntab[i] < 0)
        {
            ++values[-ntab[i]][0];
        }
        else
        {
            ++values[ntab[i]][1];
        }
    }
    cout << res;
}