Submission #2552724

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Source Code Expand

#include <algorithm>
#include <cstring>
#include <deque>
#include <functional>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <vector>
using namespace std;
using ll = long long;

int main() {
  int N, K;
  while (cin >> N >> K) {
    vector<ll> a(N), b(N);
    for (int i = 0; i < N; i++) cin >> a[i];
    for (int i = 0; i < N; i++) cin >> b[i];
    sort(a.begin(), a.end());
    sort(b.begin(), b.end());
    ll ng = 0, ok = 1ll << 60;
    while (ok - ng > 1) {
      ll m = (ng + ok) / 2;
      int j = N - 1;
      ll cnt = 0;
      for (int i = 0; i < N; i++) {
        while (j >= 0 && a[i] * b[j] > m) {
          --j;
        }
        cnt += j + 1;
      }
      if (cnt >= K) {
        ok = m;
      } else {
        ng = m;
      }
    }
    cout << ok << endl;
  }
  return 0;
}

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