#include <iostream>
#include <vector>
#include <unordered_map>
int n;
std::vector<int> v;
void input() {
std::cin >> n;
for (int i = 0; i < n; i++) {
int x;
std::cin >> x;
v.push_back(x);
}
}
void brute() {
std::vector<int> v2;
for (int i = 0; i < n; i++) {
int x = v[i];
v2.push_back(x);
// std::cout << v2.back() << "\n";
for (int j = i + 1; j < n; j++) {
x += v[j];
v2.push_back(x);
// std::cout << v2.back() << "\n";
}
}
long long result = 0;
std::unordered_map<int, int> m;
m[v2[0]] = 1;
for (int i = 1; i < v2.size(); i++) {
for (int j = i + 1; j < v2.size(); j++) {
int r = v2[i] + v2[j];
if (m.contains(-r)) {
result += m[-r];
}
}
if (m.contains(v2[i])) {
m[v2[i]]++;
} else {
m[v2[i]] = 1;
}
}
std::cout << result << "\n";
}
int main() {
std::ios_base::sync_with_stdio(false);
std::cin.tie(nullptr);
input();
brute();
return 0;
}
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 | #include <iostream> #include <vector> #include <unordered_map> int n; std::vector<int> v; void input() { std::cin >> n; for (int i = 0; i < n; i++) { int x; std::cin >> x; v.push_back(x); } } void brute() { std::vector<int> v2; for (int i = 0; i < n; i++) { int x = v[i]; v2.push_back(x); // std::cout << v2.back() << "\n"; for (int j = i + 1; j < n; j++) { x += v[j]; v2.push_back(x); // std::cout << v2.back() << "\n"; } } long long result = 0; std::unordered_map<int, int> m; m[v2[0]] = 1; for (int i = 1; i < v2.size(); i++) { for (int j = i + 1; j < v2.size(); j++) { int r = v2[i] + v2[j]; if (m.contains(-r)) { result += m[-r]; } } if (m.contains(v2[i])) { m[v2[i]]++; } else { m[v2[i]] = 1; } } std::cout << result << "\n"; } int main() { std::ios_base::sync_with_stdio(false); std::cin.tie(nullptr); input(); brute(); return 0; } |
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