poj-2492 -A Bug's Life-并查集的使用

来源：互联网发布：java读取ini配置文件编辑：程序博客网时间：2024/06/15 23:44

题目意思：

给出N条虫子，然后a和b交配，给出M对a和b后问有没有同性恋的虫子

思路：

并查集：

把相同性别的虫子连到一起，看是否有矛盾

CODE

#include<stdio.h>#include<string.h>#include<iostream>#include<algorithm>#include<stack>using namespace std;int ls[20010];int f[20010];int fid(int x){    return x == f[x] ?x:fid(f[x]);}void bc(int x,int y){    int  xx = fid(x);    int yy = fid(y);    if(xx!=yy)        f[xx] = yy;}int main(){    int t;    scanf("%d",&t);    int ki = 1;    while(t--)    {        int n, m;        scanf("%d%d",&n,&m);        memset(ls,0,sizeof(ls));        for(int i = 0; i <= n; i ++)            f[i] = i;            int flag = 0;        for(int i = 1; i <= m; i++)        {           int a, b;           scanf("%d%d",&a,&b);           if(!ls[a]&&!ls[b])           {               ls[a] = b;               ls[b] = a;           }           else if(!ls[a]&&ls[b])           {               ls[a] = b;               bc(a,ls[b]);           }           else if(ls[a]&&!ls[b])           {               ls[b] = a;               bc(b,ls[a]);           }           else           {               bc(ls[a],b);               bc(ls[b],a);           }           if(fid(a) == fid(b))            flag = 1;        }        printf("Scenario #%d:\n",ki++);        if(flag)        {            printf("Suspicious bugs found!\n");        }        else        {            printf("No suspicious bugs found!\n");        }        printf("\n");    }    return 0;}

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