HDU_find the most comfortable road(并查集)

　　去你妹的并查集，没纠结死我！按速度排序，然后枚举所有的路，知道find(start) == find(end)结束。然后用最大值减去最小值，求其差，取差最小。

Code：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>

using namespace std;

const int N = 1024;
const int inf = 0x6fffffff;

class node {
public:
    int x, y, s;
    friend bool operator < (node a, node b) {
        return a.s < b.s;
    }
}g[N];

int f[N];

int find(int x) {
    int k, r, j;
    r = k = x;
    while(r != f[r])    r = f[r];
    while(k != r)     {j = f[k]; f[k] = r; k = j;}
    return r;
}

int main() {
    //freopen("data.in", "r", stdin);

    int n, m, min, i, j, q;
    int s, e, x, y;
    while(~scanf("%d%d", &n, &m)) {
        for(i = 0; i < m; i++) {
            scanf("%d%d%d", &g[i].x, &g[i].y, &g[i].s);
        }

        sort(g, g+m);
        scanf("%d", &q);
        while(q--) {
            scanf("%d%d", &s, &e);
            for(min = inf, i = m-1; i >= 0; i--) {
                for(j = 0; j <= n; j++)     f[j] = j;
                for(j = i; j >= 0; j--) {
                    x = find(g[j].x);
                    y = find(g[j].y);
                    if(x != y)    f[x] = f[y];
                    if(find(s) == find(e))    break;

                }
                if(j >= 0 && min > g[i].s - g[j].s)
                    min = g[i].s - g[j].s;
            }
            if(min == inf)    {printf("-1\n"); continue;}
            printf("%d\n", min);
        }
    }
    return 0;
}