HDU3047+并查集

带权的并查集

/*
带权值的并查集
ps:对于两个不在同一个集合里面的两个元素，把父节点接在一起即可
*/
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<algorithm>
#include<iostream>
#include<queue>
#include<map>
#include<math.h>
using namespace std;
typedef long long ll;
//typedef __int64 int64;
const int maxn = 50015;
const int inf = 0x7fffffff;
const double pi=acos(-1.0);
const double eps = 1e-8;

int dis[ maxn ],fa[ maxn ];

void init( int n ){
    for( int i=0;i<=n;i++ ){
        dis[ i ] = 0;
        fa[ i ] = i;
    }
    return ;
}
int find( int x ){
    if( fa[x]==x ) return x;
    int tmp = find( fa[x] );
    dis[ x ] = dis[ x ]+dis[ fa[x] ];
    dis[ x ] = dis[ x ]%300;
    fa[ x ] = tmp;
    return fa[ x ];
}
bool unionab( int a,int b,int c ){
    int x = find(a);
    int y = find(b);
    //printf("fa[%d]=%d,fa[%d]=%d,dis[%d]=%d,dis[%d]=%d\n",a,x,b,y,a,dis[a],b,dis[b]);
    if( x==y ){
        if( ((dis[b]-dis[a]+300)%300)!=c ){//b在a的后面，保证是dis[b]-dis[a]
            //printf("test:%d %d\n",a,b);
            return false;
        }
    }
    else{
        dis[ y ] = dis[ a ]+c-dis[ b ]+300;
        dis[y] %= 300;
        fa[ y ] = x;
    }
    return true;
}
int main(){
    int n,m;
    while( scanf("%d%d",&n,&m)==2 ){
        int a,b,c;
        init( n );
        int res = 0;
        while( m-- ){
            scanf("%d%d%d",&a,&b,&c);
            bool f = unionab( a,b,c );
            if( f==false ) res++;
        }
        printf("%d\n",res);
    }
    return 0;
}