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
#include <bits/stdc++.h>

using namespace std;

int main() {
    std::ios::sync_with_stdio(false);
    cin.tie(NULL);

    int n;
    cin >> n;
    vector<int> ucb(n, 0);
    for (auto &a : ucb) cin >> a;
    vector<int> prefix_sums(n + 1, 0);
    for (int i = 1; i <= n; ++i)
        prefix_sums[i] = prefix_sums[i - 1] + ucb[i - 1];
    unordered_map<int, list<tuple<int, int, int>>> threes;
    long long count = 0;
    for (int i = 0; i <= n; ++i) {
        for (int j = 0; j <= n; ++j) {
            for (int k = 0; k <= n; ++k) {
                int sum = prefix_sums[i] + prefix_sums[j] + prefix_sums[k];
                auto found = threes.find(sum);
                if (found != threes.end()) {
                    for (auto[li, lj, lk] : found->second) {
                        if (li < i && lj < j && lk < k &&
                            make_pair(li, i) < make_pair(lj, j) &&
                            make_pair(lj, j) < make_pair(lk, k)) {
                            ++count;
                        }
                    }
                }
                if (i <= j && j <= k)
                    threes[sum].push_back({i, j, k});
            }
        }
    }
    cout << count << "\n";
    return 0;
}