Treasure overlap ation -- minimum path overwrite with overlapping paths

Question: http://poj.org/problem? Id = 2594

Note: use Floyd to connect an I point to a point that can be reached by I, and then overwrite the minimum path.

Source code:

#include <stdio.h>#include <string.h>#define MAXN 505int map[MAXN][MAXN];int vx[MAXN],vy[MAXN],v[MAXN];int cas,nx,ny,n,m;int uu,vv;int  dfs(int x){    v[x]=1;    for(int y=1;y<=ny;y++)     if(map[x][y]==1)     {        if(vy[y]==-1||(v[vy[y]]==0&&dfs(vy[y])))        {            vx[x]=y;  vy[y]=x;  return 1;        }     }     return 0;}int MaxMatch(){    int ans=0;    for(int i=1;i<=nx;i++)  vx[i]=-1;    for(int i=1;i<=ny;i++)  vy[i]=-1;    for(int i=1;i<=nx;i++)      {          for(int j=1;j<=nx;j++)   v[j]=0;          if(dfs(i))            ans++;      }    return ans;}int main(){    //freopen("F:\\a.txt","r",stdin);    while(1)    {        scanf("%d %d",&n,&m);        if(!n&&!m)  break;        memset(map,0,sizeof(map));        for(int i=0;i<m;i++)        {            scanf("%d %d",&uu,&vv);            map[uu][vv]=1;        }        nx=ny=n;        for(int i=1;i<=n;i++)          for(int j=1;j<=n;j++)            for(int k=1;k<=n;k++)             if(map[i][j]&&map[j][k])              map[i][k]=1;        printf("%d\n",n-MaxMatch());    }    return 0;}