HDU 3038带权并查集

#include <bits/stdc++.h>
#define ll long long
const int maxn = 1e6+10;
using namespace std;
int par[maxn];
int height[maxn];
int sum[maxn];
void init(){
    
    
   for(int i = 0; i <= maxn; i++){
    
    
        par[i] = i;
        height[i] = 0;                     //树的高度
        sum[i] = 0;
   }
}
int Find(int x){
    
    
    if(x != par[x]){
    
    
        int f = par[x];
        par[x] = Find(par[x]);   //路径压缩
        sum[x] += sum[f];
    }
    return par[x];
}
void merge_set(int a, int b,int val){
    
             //优化合并操作
    int fa = Find(a);
    int fb = Find(b);
    if (height[fa] == height[fb]) {
    
    
        height[fa] = height[fa] + 1;      //合并，树的高度加一
        par[fb] = fa;
        sum[fb] = -sum[b] + sum[a] -val;
    }
    else{
    
                                //把矮树并到高树上，高树的高度保持不变
        if (height[fa] < height[fb])  par[fa] = fb,sum[fa] = -sum[a] + sum[b] +val;
        else   par[fb] = fa,sum[fb] = -sum[b] + sum[a] -val;
    }
}
int main()
{
    
    
    int n,m;
    int ans;
    while(~scanf("%d%d",&n,&m))
    {
    
    
        ans = 0;
        init();
        int a,b,val;
        for(int i = 0;i < m;i++)
        {
    
    
            scanf("%d%d%d",&a,&b,&val);
            a--;
            int fa = Find(a);
            int fb = Find(b);
            if(fa != fb)
            {
    
    
                merge_set(a,b,val);
            }
            else{
    
    
                if(sum[a] - sum[b] != val)ans++;
            }
        }
        cout<<ans<<endl;
    }
	return 0;
}