poj 1733种类并查集+离散化

来源：互联网发布：左右声道测试软件编辑：程序博客网时间：2024/06/06 17:32

分析：http://blog.csdn.net/xiaoxiaoluo/article/details/7401172#

#include <cstdio>#include <cstring>#include <algorithm>#include <iostream>using namespace std;#define maxn 100005int n;int m;struct node{    int u,v;    int x;};node d[maxn];int num[maxn];int cnt;int r[maxn];int fa[maxn];int Bin(int x){    int low=0,high=cnt-1,mid;    while(low<=high)    {        mid=(low+high)/2;        if(num[mid]==x) return mid;        if(num[mid]<x) low=mid+1;        else high=mid-1;    }    return -1;}int find(int x){    if(x!=fa[x])    {        int f=fa[x];        fa[x]=find(fa[x]);        r[x]=r[x]^r[f];    }    return fa[x];}int main(){    cin >> n >> m;    for(int i = 0 ; i < maxn ; ++i)        fa[i] = i;    memset( r,0,sizeof(r) );    for(int i = 0 ; i < m ; ++i)    {        char str[10];        scanf("%d %d %s",&d[i].u,&d[i].v,str);        d[i].u--;        if( str[0] == 'o' )            d[i].x = 1;        else d[i].x = 0;        num[cnt++] = d[i].u, num[cnt++] = d[i].v;    }    sort(num,num+cnt);    cnt=unique(num,num+cnt)-num;   // for(int i =0;i < cnt ; ++i)printf("%d ",num[i]);    printf("\n");    int i;    for( i = 0 ; i < m ; ++i)    {        int u = Bin( d[i].u );        int v = Bin( d[i].v );        int x = find(u);        int y = find(v);      //  printf("%d %d %d %d\n",u,v,x,y);        if( x == y )        {            if( r[u] == r[v] && d[i].x == 1 )break;            if( r[u] != r[v] && d[i].x == 0 )break;        }        else        {            if(d[i].x==1)            {                fa[x]=y;                r[x]=r[u]^r[v]^1;            }            else            {                fa[x]=y;                r[x]=r[u]^r[v];            }        }    }    printf("%d\n",i);}

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