poj 1422 最小路径覆盖

//可转换为二分匹配
#include <iostream>
#include <cstring>
using namespace std;
#define MAXN 122

int T;
int n,m;

int G[MAXN][MAXN];

int cx[MAXN],cy[MAXN];
int sx[MAXN],sy[MAXN];

int path(int u)
{
sx[u] = 1;
for(int v = 1; v <= n;v++)
{
if(G[u][v] > 0 && (!sy[v]))
{
sy[v] = 1;
if(!cy[v] || path(cy[v]))
{
cx[u] = v;
cy[v] = u;
return 1;
}
}
}
return 0;
}

int MaxMatch()
{
int res = 0;
memset(cx,0,sizeof(cx));
memset(cy,0,sizeof(cy));
for(int i = 1; i <= n; i++)
{
if(!cx[i])
{
memset(sx,0,sizeof(sx));
memset(sy,0,sizeof(sy));
res += path(i);
}
}
return res;
}

int main()
{
cin>>T;
while(T--)
{
memset(G,0,sizeof(G));
cin>>n>>m;
while(m--)
{
int x,y;
cin>>x>>y;
G[x][y] = 1;
}
cout<<n - MaxMatch()<<endl;
}
return 0;
}