Language: C++

#include <atcoder/all>

#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#include <deque>
#include <list>
#include <queue>
#include <stack>
#include <vector>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <complex>
#include <cmath>
#include <limits>
#include <climits>
#include <ctime>
#include <cassert>
#include <numeric>
#include <functional>
#include <bitset>

using namespace std;
using namespace atcoder;
using lint = long long int;
long long int INF = 100100101LL;
int inf = 1000000007;
long long int MOD = 1000000007LL;
double PI = 3.1415926535897932;

template<typename T1,typename T2>inline void chmin(T1 &a,const T2 &b){if(a>b) a=b;}
template<typename T1,typename T2>inline void chmax(T1 &a,const T2 &b){if(a<b) a=b;}

#define ALL(a) a.begin(),a.end()
#define RALL(a) a.rbegin(),a.rend()

/* do your best */

// 最小費用流
// O(F E log V)
// 与えられるもの
// 有向グラフ G = (V, E)
// 各辺 e に対して, 容量 u(e) >= 0
// 各辺 e に対して, 費用 c(e) (負でも ok)

// 使い方
// PrimalDual(V) (コンストラクタ)
// add_edge(int from, int to, flow_t cap, cost_t cost)
// cost に関する負の閉路が存在する場合,だめ
// veryfied : http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_6_B&lang=jp
// 流れなかったら -1 を返す



template< typename flow_t, typename cost_t >
struct PrimalDual{
    const cost_t INF;

    struct edge {
        int to;
        flow_t cap;
        cost_t cost;
        int rev;
        bool isrev;
    };
    vector<vector<edge>> graph;
    vector<cost_t> potential, min_cost;
    vector<int> prevv, preve;

    PrimalDual(int V) : graph(V), INF(numeric_limits< cost_t >::max()){}

    void add_edge(int from, int to, flow_t cap, cost_t cost){
        graph[from].emplace_back((edge) {to, cap, cost, (int)graph[to].size(), false});
        graph[to].emplace_back((edge) {from, 0, -cost, (int)graph[from].size() - 1, true});
    }

    cost_t min_cost_flow(int s, int t, flow_t f){
        int V = (int) graph.size();
        cost_t ret = 0;
        using Pi = pair< cost_t, int >;
        priority_queue< Pi, vector< Pi >, greater< Pi > > que;
        potential.assign(V, 0);
        preve.assign(V, -1);
        prevv.assign(V, -1);

        while(f > 0){
            min_cost.assign(V, INF);
            que.emplace(0, s);
            min_cost[s] = 0;
            while(!que.empty()){
                Pi p = que.top();
                que.pop();
                if(min_cost[p.second] < p.first) continue;
                for(int i = 0; i < graph[p.second].size(); i++){
                    edge &e = graph[p.second][i];
                    cost_t nextCost = min_cost[p.second] + e.cost + potential[p.second] - potential[e.to];
                    if(e.cap > 0 && min_cost[e.to] > nextCost){
                        min_cost[e.to] = nextCost;
                        prevv[e.to] = p.second, preve[e.to] = i;
                        que.emplace(min_cost[e.to], e.to);
                    }
                }
            }
            if(min_cost[t] == INF) return -1;
            for(int v = 0; v < V; v++) {
              min_cost[v] %= MOD;
              potential[v] += min_cost[v];
              potential[v] %= MOD;
            }
            flow_t addflow = f;
            for(int v = t; v != s; v = prevv[v]){
                addflow = min(addflow, graph[prevv[v]][preve[v]].cap);
            }
            f -= addflow;
            ret += addflow * potential[t];
            for(int v = t; v != s; v = prevv[v]){
                edge &e = graph[prevv[v]][preve[v]];
                e.cap -= addflow;
                graph[v][e.rev].cap += addflow;
            }
        }
        return ret;
    }

    void output(){
        for(int i = 0; i < graph.size(); i++){
            for(auto &e : graph[i]) {
                if(e.isrev) continue;
                auto &rev_e = graph[e.to][e.rev];
                cout << i << "->" << e.to << " (flow: " << rev_e.cap << "/" << rev_e.cap + e.cap << ")" << endl;
            }
        }
    }
};

int main() {
  
  int n, m; cin >> n >> m;
  vector<vector<char>> s(n, vector<char>(m));
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      cin >> s[i][j];
    }
  }

  PrimalDual<lint, lint> g(n * m + 2);
  int source = n * m;
  int sink = n * m + 1;

  int cnt = 0;

  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (s[i][j] == '#') continue;

      if (s[i][j] == 'o') {
        cnt++;
        int from = source;
        int to = i * m + j;
        lint cap = 1;
        lint cost = 0; 
        g.add_edge(from, to, cap, cost);
      }
      { 
        int from = i * m + j;
        int to = sink;
        lint cap = 1;
        lint cost = 0;
        g.add_edge(from, to, cap, cost);
      }

      if ((i + 1) < n) {
        int from = i * m + j;
        int to = (i + 1) * m + j;
        lint cap = 1e9;
        lint cost = -1;
        g.add_edge(from, to, cap, cost);
      }

      if ((j + 1) < m) {
        int from = i * m + j;
        int to = i * m + j + 1;
        lint cap = 1e9;
        lint cost = -1;
        g.add_edge(from, to, cap, cost);
      }
    }
  }

  cout << -g.min_cost_flow(source, sink, cnt) << endl;
  return 0;
}


Compiler output:
a.cc:1:10: fatal error: atcoder/all: No such file or directory
    1 | #include <atcoder/all>
      |          ^~~~~~~~~~~~~
compilation terminated.