Submission #169416

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Source Code Expand

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

const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, 1, 0, -1};

int solve(int idx, deque<deque<bool> >& field, const vector<pair<int, int> >& p) {
  const int N = (int)p.size();
  const int W = (int)field[0].size();
  const int H = (int)field.size();

  if (idx >= N) {
    int cnt = 0;
    for (int i = 0; i < H; ++i) {
      cnt += count(field[i].begin(), field[i].end(), false);
    }
    return cnt;
  }

  field[p[idx].second][p[idx].first] = false;
  for (int d = 0; d < 4; ++d) {
    int x = p[idx].first + dx[d];
    int y = p[idx].second + dy[d];

    while (0 <= x && x < W && 0 <= y && y < H && field[y][x]) {
      field[y][x] = false;
      x += dx[d];
      y += dy[d];
    }
  }

  return solve(idx+1, field, p);
}

int main() {
  int W, H, N;
  while (cin >> W >> H >> N) {
    if (N > 8 || W > 80 || H > 80) {
      cout << "0" << endl;
      continue;
    }

    vector<pair<int, int> > p(N);
    for (int i = 0; i < N; ++i) {
      cin >> p[i].first >> p[i].second;
      --p[i].first;
      --p[i].second;
    }
    sort(p.begin(), p.end());

    int ans = 0;
    do {
      deque<deque<bool> > field(H, deque<bool>(W, true));
      ans = max(ans, solve(0, field, p));
    } while (next_permutation(p.begin(), p.end()));

    cout << ans << endl;
  }
  return 0;
}

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