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

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题目：

链接：点击打开链接

思路：

对边排序，再枚举每条边，如果出现通路（findset(x) == findset(y)）就结束。

代码：

#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>using namespace std;#define MAXN 220#define MAXM 1010#define MAX 100000000struct node{    int s,e,w;}edge[MAXM];int root[MAXN];int n,m,q;int cmp(node a,node b){    return a.w < b.w;}int findset(int x){    return root[x] == x ? x : root[x] = findset(root[x]);}void mergeset(int x,int y){    root[findset(x)] = findset(y);}void init(){    for(int i=1; i<=n; i++)        root[i] = i;}int main(){    //freopen("input.txt","r",stdin);    int x,y;    int minn;    while(scanf("%d%d",&n,&m) != EOF)    {        int i,j;        for(i=0; i<m; i++)        {            scanf("%d%d%d",&edge[i].s,&edge[i].e,&edge[i].w);        }        sort(edge,edge+m,cmp);        scanf("%d",&q);        while(q--)        {            scanf("%d%d",&x,&y);            minn = MAX;            for(i=0; i<m; i++)            {                init();                for(j=i; j<m; j++)                {                    mergeset(edge[j].s,edge[j].e);                    if(findset(x) == findset(y))                        break;                }                if(j == m)                    break;                if(minn > edge[j].w - edge[i].w)                    minn = edge[j].w - edge[i].w;            }            if(minn == MAX)                printf("-1\n");            else                printf("%d\n",minn);        }    }    return 0;}

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