[백준,c++] 1253번 - 좋다

1253번: 좋다

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    int N; cin >> N;
    vector<int>v(N);

    for (int i = 0; i < N; i++) {
        cin >> v[i];
    }
    sort(v.begin(), v.end());    //이분탐색을 위한 정렬
    int cnt = 0;
    for (int i = 0; i < N; i++) {
        int start = 0;
        int end = N - 1;
        while (start < end) {
            if (v[start] + v[end] == v[i]) {
                if (start != i && end != i) {
                    cnt++;
                    break;
                }
                else if (start == i) start++;
                else if (end== i) end--;

            }
            else if (v[start] + v[end] < v[i]) start++;
            else end--;
        }
    }

    cout << cnt;

}