DFSCount.cpp

#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <unordered_map>
#include <unordered_set>
#include <tuple>

using namespace std;

class DFSCountEasy {
public:
    long long f[9000][13];
    bool visit[13];
    void dfs(vector<string>& G, int k) {
        visit[k] = 1;
        for (int i=0; i<G.size(); i++) {
            if (G[k][i] == 'Y' && !visit[i])
                dfs(G, i);
        }
    }
    long long solve(vector<string>& G, int mask, int cur) {
        if (f[mask][cur] == -1) {
            f[mask][cur] = 0;
            for (int i=0; i<G.size(); i++) {
                if (G[cur][i] == 'N' || (mask & (1<<i))) continue;
                memset(visit, 0, sizeof(visit));
                for (int j=0; j<G.size(); j++) {
                    if (mask & (1<<j)) visit[cur] = 1;
                }
                dfs(G, i);
                int nmask = 0;
                for (int j=0; j<G.size(); j++) {
                    if (visit[j]) nmask |= (1 << j);
                }
                f[mask][cur] += solve(G, mask|(1<<i), i) * solve(G, mask|nmask, cur);
            }
            f[mask][cur] = max(1LL, f[mask][cur]);
        }
        return f[mask][cur];
    }
    long long count(vector <string> G) {
        memset(f, -1, sizeof(f));
        int n = G.size();
        long long ans = 0;
        for (int i=0; i<n; i++) {
            ans += solve(G, 1<<i, i);
            cout<<solve(G, 1<<i, i)<<endl;
        }
        return ans;
    }
};