UVA-1160 - X-Plosives（并查集）

一道简单的并查集。。题意其实就是判断是否有环。。

// File Name: 1160.cpp
// Author: zlbing
// Created Time: 2013/3/8 21:26:11

#include<iostream>
#include<string>
#include<algorithm>
#include<cstdlib>
#include<cstdio>
#include<set>
#include<map>
#include<vector>
#include<cstring>
#include<stack>
#include<cmath>
#include<queue>
using namespace std;
#define CL(x,v); memset(x,v,sizeof(x));
#define INF 0x3f3f3f3f
#define LL long long
#define REP(i,n) for(int i=0;i<n;i++)
#define REP1(i,n) for(int i=1;i<n+1;i++)
const int MAXN=100050;
int f[MAXN];
int find(int x){
    return x==f[x]?x:f[x]=find(f[x]);
}
int main(){
    int a,b;
    while(~scanf("%d",&a)){
    int ans=0;
    REP1(i,MAXN-5)f[i]=i;
        while(a!=-1){
        scanf("%d",&b);
        int fx=find(a);
        int fy=find(b);
        if(fx==fy)ans++;
        else f[fx]=fy;
        scanf("%d",&a);
        }
    printf("%d\n",ans);
    }
    return 0;
}

 

转载于:https://www.cnblogs.com/arbitrary/archive/2013/03/08/2950808.html