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BOJ. Castle Difense (17135)

[Link] https://www.acmicpc.net/problem/17135


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#include <algorithm>
#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <cstring>
#include <stack>
// #include <bits/stdc++.h>
using namespace std;
#define for0(i, n) for(int i = 0; i < n; i++)
#define for1(i, n) for(int i = 1; i < n; i++)
#define fori(s, e) for(int i = s; i < e; i++)
#define ll long long
#define endl "\n"
#define nulls '\0'
#define dkdk " "
const int MAX = 5e5 + 1;
const int INF = 987654321;

int n, m, d, ans, enemy_cnt;
bool mm[15][15];
bool tmp[15][15];
bool swap_arr[15][15];
set<pair<int,int>> kill;
vector<int> list;

void calc() {
  for0(i, n) for0(j, m) tmp[i][j] = mm[i][j];
  int e_cnt = enemy_cnt, kill_cnt = 0;
  while(e_cnt) {
    kill.clear();
    for0(k, 3) {
      memset(swap_arr, 0, sizeof(swap_arr));
      int min_dis = INF, ii = 0, jj = 0;
      for0(i, n) for0(j, m) {
        if(tmp[i][j] == false) continue;
        if(abs(j - list[k]) + n - i == min_dis) {
          if(j < jj) ii = i, jj = j;
        }
        else if(abs(j - list[k]) + n - i < min_dis) {
          min_dis = abs(j - list[k]) + n - i;
          ii = i, jj = j;
        }
      }
      if(min_dis <= d) kill.insert({ ii, jj });
    }
    kill_cnt += (int)kill.size();
    for(auto p: kill) tmp[p.first][p.second] = false;
    for0(i, n-1) for0(j, m) swap_arr[i+1][j] = tmp[i][j];
    e_cnt = 0;
    for0(i, n) for0(j, m) { tmp[i][j] = swap_arr[i][j]; if(tmp[i][j]) e_cnt++; }
  }
  ans = max(ans, kill_cnt);
}

void dfs(int startIdx) {
  if(list.size() == 3) {
    calc();
    return;
  }
  for(int i = startIdx; i < m; i++) {
    list.push_back(i);
    dfs(i+1);
    list.pop_back();
  }
}

int main() {
  ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  cin >> n >> m >> d;
  for0(i, n) for0(j, m) {
    int in; cin >> in;
    if(in) { enemy_cnt++; mm[i][j] = true; }
  }
  dfs(0);
  cout << ans;
  return 0;
}
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