HDU - 1083 Courses(二分圖匹配)

HDU - 1083 

題意：就是求最大匹配是否是完美匹配。

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>

using namespace std;
const int maxn = 500,maxe = 3e5;
struct node
{
    int to,next;
    node(){}
    node(int a,int b){to = a; next = b;}
}edge[maxe << 1];
int edgenum;
int h[maxn],used[maxn],belong[maxn];
void add(int f,int t)
{
    edge[edgenum] = node(t,h[f]);
    h[f] = edgenum++;
}
void init()
{
    edgenum = 0;
    for(int i = 0; i < maxn; i++)
        h[i] = -1, belong[i] = used[i] = 0;
}
bool Find(int u)
{
    for(int i = h[u]; ~i; i = edge[i].next)
    {
        int v = edge[i].to;
        if(used[v]) continue;
        used[v] = 1;
        if(belong[v]==0 || Find(belong[v]))
        {
            belong[v] = u;
            return true;
        }
    }
    return false;
}
int main()
{
    int t,pnum,v,p,n;
    scanf("%d",&t);
    while(t--)
    {
        init();
        scanf("%d%d",&p,&n);
        for(int i = 1; i <= p ; i++)
        {
            scanf("%d",&pnum);
            for(int j = 0; j < pnum; j++)
            {
                scanf("%d",&v);
                add(i,v+p);   add(v+p,i);
            }
        }
        int ans = 0;
        for(int i = 1; i <= p; i++)
        {
            memset(used,0,sizeof(used));
            if(Find(i)) ans ++;
        }
        ans == p ? printf("YES\n") : printf("NO\n");
    }
    return 0;
}