Poj2239 Selecting Courses --- maximum matching of a Bipartite Graph

Algorithm template question in Hungary

There are n courses, and each course may have different time periods. different time periods are equivalent.

Ask the maximum number of courses that can be selected without conflict.

Create a bipartite graph. One vertex indicates different courses, and the other vertex indicates the course time (hash ).

#include <iostream>#include <cstring>#include <string>#include <cstdio>#include <cmath>#include <algorithm>#include <vector>#include <queue>#include <map>#define inf 0x3f3f3f3f#define eps 1e-6#define ll __int64using namespace std;int mp[310][310],used[310],link[310],n,m;bool dfs(int x){    for(int i=1;i<=m;i++)    {        if(!used[i]&&mp[x][i])        {            used[i]=1;            if(link[i]==-1||dfs(link[i]))            {                link[i]=x;                return 1;            }        }    }    return 0;}int hungry(){    int res=0;    memset(link,-1,sizeof link);    for(int i=1;i<=n;i++)    {        memset(used,0,sizeof used);        if(dfs(i))            res++;    }    return res;}int main(){    int i,a,b;    while(~scanf("%d",&n))    {        memset(mp,0,sizeof mp);        for(i=1;i<=n;i++)        {            scanf("%d",&m);            while(m--)            {                scanf("%d%d",&a,&b);                mp[i][(a-1)*12+b]=1;            }        }        m=7*12;        printf("%d\n",hungry());    }    return 0;}