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
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
#include <bits/stdc++.h>
#define int long long
using namespace std;

int Ccc(int n, int k) {
    double res = 1;
    for (int i = 1; i <= k; ++i)
        res = res * (n - k + i) / i;
    return (int)(res + 0.01);
}

int cc3(int n){
    return Ccc(n, 3);
}

int32_t main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    int n;
    cin >> n;
    vector <int> a(n);
    for(int i = 0; i < n; i++)
        cin >> a[i];
    vector <int> presum(n+2, 0);
    presum[0];
    for(int i = 1; i <= n; i++)
        presum[i] = presum[i-1] + a[i-1];
    vector <int> sums;
    for(int i = 0; i < n; i++)
    for(int j = i+1; j <= n; j++){
        sums.push_back(presum[j] - presum [i]);
    }
    sort(sums.begin(), sums.end());
    vector <int> sum2;
    vector <int> mp(20000010);

    for(auto x: sums){
        mp[10000000+x]++;
        if(mp[10000000+x] == 1)
            sum2.push_back(x);
    }

    int c1 = 0, c2 = 0, c3 = 0;
    for(auto x: sum2)
    {
        for(auto y: sum2)
        {
            int z = - x - y;
            if(mp[10000000+z] > 0)
            {
                if(x == y and mp[10000000+x] < 2)
                {}
                else if(x == z and mp[10000000+x] < 2)
                {}
                else if(z == y and mp[10000000+z] < 2)
                {}
                else if(z == y and x == z and mp[10000000+z] < 3)
                {}
                else if(x != y and y != z and x != z)
                {
                    c3 += mp[10000000+x]*mp[10000000+y]*mp[10000000+z];
                }
                else if(x == y and y == z){
                    c1 += cc3(mp[10000000+x]);
                }
                else if(x == y)
                {
                    c2 += Ccc(mp[10000000+x], 2)*mp[10000000+z];
                }
                else if(x == z)
                {
                    c2 += Ccc(mp[10000000+x], 2)*mp[10000000+y];
                }
                else if(z == y)
                {
                    c2 += Ccc(mp[10000000+z], 2)*mp[10000000+x];
                }
            }
        }
    }
    cout << c1 + c2/3 + c3/6;

    return 0;
}