2022/round3/fourth_player.cpp

#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;

int solve() {
  int N;
  cin >> N;
  vector<vector<int>> C(2);
  for (int i = 0; i < 4; i++) {
    vector<int> H(N/4);
    for (int j = 0; j < N/4; j++) {
      cin >> H[j];
    }
    sort(H.begin(), H.end());
    if (i == 0) {
      C[0] = H;
    } else {
      int us = i % 2, them = 1 - us;
      vector<vector<int>> C2(2);
      // Cover as many of their team's highest cards as possible.
      for_each(C[them].rbegin(), C[them].rend(), [&](int card) {
        if (!H.empty() && H.back() > card) {
          C2[us].push_back(H.back());
          H.pop_back();
        } else {
          C2[them].push_back(card);
        }
      });
      // Cover as many of our team's lowest cards as possible.
      for (int card : C[us]) {
        if (!H.empty() && H.back() >= card) {
          C2[us].push_back(H.back());
          H.pop_back();
        } else {
          C2[us].push_back(card);
        }
      }
      C = C2;
      sort(C[us].begin(), C[us].end());
      sort(C[them].begin(), C[them].end());
    }
  }
  return C[0].size();
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  int T;
  cin >> T;
  for (int t = 1; t <= T; t++) {
    cout << "Case #" << t << ": " << solve() << endl;
  }
  return 0;
}