[bzoj1854][Scoi2010]游戏（并查集/二分图最大匹配）

【题目链接】http://www.lydsy.com/JudgeOnline/problem.php?id=1854
【解题思路】二分图匹配顺序增广即可，还有神奇的并查集做法，详见黄学长博客（http://hzwer.com/2950.html）
【呆马（并查集）】

#include<cstdio>#include<algorithm>#include<cmath>#include<cstdlib>#include<iostream>const int N=1e4+10;using namespace std;int n,x,y,i,fa[N],f[N];int find(int x){return fa[x]==x?x:fa[x]=find(fa[x]);}int main(){    freopen("bzoj1854.in","r",stdin);    freopen("bzoj1854.out","w",stdout);        scanf("%d\n",&n);        for (i=1;i<=10000;i++) fa[i]=i;        for (i=1;i<=n;i++)        {            scanf("%d%d\n",&x,&y);            x=find(x);            y=find(y);            if (x==y) f[x]=1;            else            {                if (x>y) swap(x,y);                fa[x]=y;                f[x]=1;            }        }        for (i=1;i<=n+1;i++)            if (!f[i])            {                printf("%d",i-1);                return 0;            }    fclose(stdin);    fclose(stdout);}