hdu3038 How Many Answers Are Wrong 种类并查集

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

int n, m;
const int maxn = 200005;
int fa[maxn];
int sum[maxn];

int Find(int x){
    if (x == fa[x])
        return x;
    else{
        int t = fa[x];
        fa[x] = Find(fa[x]);
        sum[x] += sum[t];
        return fa[x];
    }
}

bool Set_Union(int x, int y, int s){
    int fx = Find(x);
    int fy = Find(y);
    if (fx == fy && sum[x] != sum[y] + s)
        return false;
    else if(fx != fy){
        if (fx > fy){
            fa[fy] = fx;
            sum[fy] = sum[x] - s - sum[y];
        }
        else{
            fa[fx] = fy;
            sum[fx] = s + sum[y] - sum[x];
        }
    }
    return true;
}

void init(){
    memset(sum, 0, sizeof(sum));    //必须初始化为零
    for (int i = 0; i <= n; i++){
        fa[i] = i;
    }
}

int main(){
    while (scanf("%d %d", &n, &m) != EOF){
        init();        //初始化
        int ans = 0;
        while (m--){
            int a, b, s;
            scanf("%d%d%d", &a, &b, &s);
            a--;
            if (!Set_Union(a, b, s)){
                ans++;
            }
        }
        printf("%d
", ans);
    }
    //system("pause");
    return 0;
}