블랙 프라이데이 [C++]

출처

• 2019 Sogang Programming Contest Master C번

문제

링크

풀이

#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;
 
bool solve(void) {
  int n, c; cin >> n >> c;
  vector<int> w(n);
  for (int i=0; i<n; i++) cin >> w[i];
  sort(w.begin(), w.end());
 
  // one
  if (binary_search(w.begin(), w.end(), c)) return true;
 
  // two
  for (int i=0; i<n; i++) {
    if (binary_search(w.begin()+i+1, w.end(), c-w[i])) return true;
  }
 
  // three
  for (int i=0; i<n-1; i++) for (int j=i+1; j<n; j++) {
    if (binary_search(w.begin()+j+1, w.end(), c-w[i]-w[j])) return true;
  }
  return false;
}
 
int main(void) {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
 
  cout << solve();
  return 0;
}