【2018年全国多校算法寒假训练营练习比赛(第四场)-A】石油采集(匈牙利算法)

#include<bits/stdc++.h>
using namespace std;
char mp[55][55];
bool vis[2505];
vector<int>G[2505];
int mp1[55][55], match[2505], n;
bool dfs(int u)
{
    for(int i = 0; i < G[u].size(); i++)
    {
        int v = G[u][i];
        if(!vis[v])
        {
            vis[v] = 1;
            if(match[v] == -1 || dfs(match[v]))
            {
                match[v] = u;
                return 1;
            }
        }
    }
    return 0;
}
int main()
{
    int t, cas = 0;
    cin>>t;
    while(t--)
    {
        int num = 0;
        scanf("%d", &n);
        for(int i = 0; i < n; i++) scanf("%s", mp[i]);
        for(int i = 0; i < n; i++)
            for(int j = 0; j < n; j++)
                if(mp[i][j] == ‘#‘) mp1[i][j] = ++num;
        for(int i = 0; i < n; i++)
            for(int j = 0; j < n; j++)
            {
                if(mp[i][j] == ‘#‘)
                {
                    if(mp[i+1][j] == ‘#‘) G[mp1[i][j]].push_back(mp1[i+1][j]), G[mp1[i+1][j]].push_back(mp1[i][j]);
                    if(mp[i][j+1] == ‘#‘) G[mp1[i][j]].push_back(mp1[i][j+1]), G[mp1[i][j+1]].push_back(mp1[i][j]);
                }
            }
        memset(match, -1, sizeof match);
        int ans = 0;
        for(int i = 1; i <= num; i++)
        {
            memset(vis, 0, sizeof vis);
            if(dfs(i)) ans++;
        }
        printf("Case %d: %d\n", ++cas, ans/2);
    }
    return 0;
}