[POJ 1422] Air Raid

[题目链接]

          http://poj.org/problem?id=1422

[算法]

       二分图最小路径点覆盖

[代码]

        

#include <algorithm>  
#include <bitset>  
#include <cctype>  
#include <cerrno>  
#include <clocale>  
#include <cmath>  
#include <complex>  
#include <cstdio>  
#include <cstdlib>  
#include <cstring>  
#include <ctime>  
#include <deque>  
#include <exception>  
#include <fstream>  
#include <functional>  
#include <limits>  
#include <list>  
#include <map>  
#include <iomanip>  
#include <ios>  
#include <iosfwd>  
#include <iostream>  
#include <istream>  
#include <ostream>  
#include <queue>  
#include <set>  
#include <sstream>  
#include <stdexcept>  
#include <streambuf>  
#include <string>  
#include <utility>  
#include <vector>  
#include <cwchar>  
#include <cwctype>  
#include <stack>  
#include <limits.h>
using namespace std;
#define MAXN 210

int i,n,m,u,v,T,ans;
int match[MAXN];
bool g[MAXN][MAXN];
bool visited[MAXN];

inline bool hungary(int u)
{
        int v;
        for (v = 1; v <= n; v++)
        {
                if (g[u][v] && !visited[v])
                {
                        visited[v] = true;
                        if (!match[v] || hungary(match[v]))
                        {
                                match[v] = u;
                                return true;
                        }
                }
        }
        return false;        
}

int main() 
{
        
        scanf("%d",&T);
        while (T--)
        {
                memset(g,false,sizeof(g));
                memset(match,0,sizeof(match));
                scanf("%d%d",&n,&m);
                for (i = 1; i <= m; i++)
                {
                        scanf("%d%d",&u,&v);
                        g[u][v] = true;
                } 
                ans = 0;
                for (i = 1; i <= n; i++)
                {
                        memset(visited,false,sizeof(visited));
                        if (hungary(i)) ans++;
                }
                printf("%d
",n - ans);
        }
        
        return 0;
    
}