🐣 문제

링크 : https://www.acmicpc.net/problem/3273

🐥 코드

/*
문제 : 두 수의 합
링크 : https://www.acmicpc.net/problem/3273
*/

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
vector<int> v;
int main(){
    int n;
    cin >> n;
    
    for(int i = 0, tmp; i<n; i++){
        cin >> tmp;
        v.push_back(tmp);
    }

    int target;
    cin >> target;

    sort(v.begin(), v.end());
    int start = 0, end = n-1, cnt = 0;

    while(start < end){
        if(v[start] + v[end] == target){
            cnt ++;
            end --;
            start ++;
        }

        else if(v[start] + v[end] >= target) end --;
        else start ++;
    }

    cout << cnt; 
    return 0;
}