POJ 1422

#include <iostream>
#define MAXN 350
using namespace std;

int mat[MAXN][MAXN];
bool mark[MAXN];
int match[MAXN];
int graph_match(int n,int mat[][MAXN],int * match);
int main()
{
//freopen("acm.acm","r",stdin);
int test;
int n;
int m;
int u;
int v;
int i;
int j;
cin>>test;
while(test --)
{
memset(mat,0,sizeof(mat));
memset(match,-1,sizeof(match));
cin>>n;
cin>>m;
for(i = 0; i < m; ++ i)
{
cin>>u;
cin>>v;
-- u;
-- v;
mat[u][v+n] = 1;
}

cout<<n-graph_match(n*2,mat,match)<<endl;
}

}

//一般图最大匹配,邻接阵形式,复杂度O(n^3)
//返回匹配顶点对数,match返回匹配,未匹配顶点match值为-1
//传入图的顶点数n和邻接阵mat
//graph_match（）为最终调用函数

int aug(int n,int mat[][MAXN],int* match,int* v,int now){
int i,ret=0;
v[now]=1;
for (i=0;i<n;i++)
if (!v[i]&&mat[now][i]){
if (match[i]<0)
match[now]=i,match[i]=now,ret=1;
else{
v[i]=1;
if (aug(n,mat,match,v,match[i]))
match[now]=i,match[i]=now,ret=1;
v[i]=0;
}
if (ret)
break;
}
v[now]=0;
return ret;
}
int graph_match(int n,int mat[][MAXN],int * match){
int v[MAXN],i,j;
for (i=0;i<n;i++)
v[i]=0,match[i]=-1;
for (i=0,j=n;i<n&&j>=2;)
if (match[i]<0&&aug(n,mat,match,v,i))
i=0,j-=2;
else
i++;
for (i=j=0;i<n;i++)
j+=(match[i]>=0);
return j/2;
}