【模板】最小生成树

洛谷P3366 

kruskal算法基于并查集思想qwq

prim我不会吖QAQ

#include<cstdio>
#include<iostream>
#include<algorithm>
#define maxn 5050
#define maxm 200020
using namespace std;
int n,m,num = 0,ans = 0;
int f[maxn];
struct edge {
    int u, v, w;
}e[maxm];
bool cmp(edge a,edge b) {
    if(a.w == b.w) return a.u <b.u;
    return a.w < b.w;
}
int init(int x) {for(int i = 1; i <= x; i++) f[i] = i;}
int find(int x) {
    if(x != f[x]) f[x] = find(f[x]);
    return f[x];
}
void merge(int x,int y) {f[y] = x;}
int main() {
    scanf("%d%d",&n,&m);
    init(n);
    for(int i = 1; i <= m; i++) scanf("%d%d%d",&e[i].u,&e[i].v,&e[i].w);
    sort(e+1,e+m+1,cmp);
    for(int i = 1; i <= m; i++) {
        int r1 = find(e[i].u), r2 = find(e[i].v);
        if(r1 != r2) {
            merge(r1,r2);
            ans += e[i].w;
            num++;
        }
        if(num == n-1) {
            printf("%d",ans);
            return 0;
        }
    }
    printf("orz");
    return 0;
}