洛谷 P1396 营救

题目传送门

解题思路:

跑Kruskal,直到s与t联通,输出最大值

AC代码:

#include<cstdio>
#include<iostream>
#include<algorithm>

using namespace std;

int n,m,s,t,fa[10001],ans;
struct kkk {
    int from,to,v;
}e[20001];

bool cmp(kkk a,kkk b) {
    return a.v < b.v;
}

int find_father(int x) {
    if(fa[x] == x) return x;
    return fa[x] = find_father(fa[x]);
}

int main()
{
    scanf("%d%d%d%d",&n,&m,&s,&t);
    for(int i = 1;i <= n; i++)
        fa[i] = i;
    for(int i = 1;i <= m; i++) 
        scanf("%d%d%d",&e[i].from,&e[i].to,&e[i].v);
    sort(e+1,e+m+1,cmp);
    for(int i = 1;i <= m; i++) {
        int x1 = find_father(e[i].from);
        int y1 = find_father(e[i].to);
        if(x1 != y1) {
            fa[x1] = y1;
            ans = max(ans,e[i].v);
        }
        if(find_father(s) == find_father(t)) {
            printf("%d",ans);
            return 0;
        }
    }
    return 0;
}