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HDU 1598 find the most comfortable road(并查集+枚举)

先把每条边的权值从大到小排序,在一个个枚举,利用并查集判断是否在一个集合中。。。

<span style="font-size:24px;">#include<stdio.h>
#include<string.h>
#include<algorithm>
#include<iostream>
#include<stdlib.h>
#include<cmath>
using namespace std;
const int maxn=205;
const int maxm=1005;
const int inf=(0x7f7f7f7f);
#define min(a,b) ((a)<(b)?(a):(b))
int fa[maxn];
int n,m;
struct node
{
    int x,y,z;
}p[maxm];
bool cmp(node g,node h)
{
    return g.z<h.z;
}
int find(int x)
{
    while (fa[x] != x) x = fa[x];
    return x;
}
int main()
{
    int s,t;
    while(~scanf("%d%d",&n,&m))
    {
        int i,j;
        for(i=0;i<m;i++)
            scanf("%d%d%d",&p[i].x,&p[i].y,&p[i].z);
        sort(p,p+m,cmp);
        int q;
        scanf("%d",&q);
        while(q--)
        {
            scanf("%d%d",&s,&t);
            int min1=inf;
            for(j=0;j<m;j++){
            for(i=1;i<=n;i++)
                fa[i]=i;
            for(i=j;i<m;i++)
            {
                int fy=find(p[i].y);
                int fx=find(p[i].x);
                if(fy!=fx)
                    fa[fy]=fx;
                if(find(s)==find(t))
                {
                   min1=min(min1,p[i].z-p[j].z); break;
                }
            }
            }
            if(min1==inf)
                puts("-1");
            else
                printf("%d\n",min1);
        }
    }
    return 0;
}</span>