hdu 1598 find the most comfortable road

题目要求是可达情况下，舒适度最好，即速度之差最小。

1.因为不考虑距离 所以只要在同一集合中即可

2.需要在条件1下枚举最小速度，然后找符合条件的

#include "iostream"
#include "algorithm"
#include "memory.h"
#include "cmath"
#include "string"
#include "vector"
#include "algorithm"
#include "climits"
using namespace std;
#define MAXN 1111
#define _min(a,b) (((a)<(b))?(a):(b))
struct node {
    int x, y,speed;
    bool operator < (node a) const{
        return speed < a.speed;
    }
}p[MAXN];
int fa[MAXN];
int n, m, q, t;
int re, num, ans;

int find(int x)
{
    if (fa[x] < 0) return x;
    return fa[x] = find(fa[x]);
}

void merge(int a, int b)
{
    int x = find(a);
    int y = find(b);
    if (x < y) {
        fa[x] += fa[y];
        fa[y] = x;
    }
    if (x > y) {
        fa[y] += fa[x];
        fa[x] = y;
    }
}


int main()
{
    ios::sync_with_stdio(false);
    while (cin >> n >> m) {
        for (int i = 0; i < m; ++ i) {
            cin >> p[i].x >> p[i].y >> p[i].speed;
        }
        sort(p,p+m);
        cin >> q;
        for (int i = 0; i < q; ++i) {
            int u, v;
            cin >> u >> v;
            ans = INT_MAX;
            for (int j = 0; j < m; ++j) {
                memset(fa,-1,sizeof(fa));
                for (int k = j; k < m; ++k) {
                    merge(p[k].x,p[k].y);
                    if (find(u) == find(v)) {
                        ans = _min(ans, p[k].speed - p[j].speed);
                        break;
                    }
                }
            }
            if (ans == INT_MAX) cout << "-1" << endl;
            else cout << ans << endl;
        }
    }
    return 0;
}