个人模板 prim 最小生成树

#include<bits/stdc++.h>

using namespace std;

const int Inf = 0x3f3f3f3f;
const int N = 1e4 + 10;
int n, m;
int a[N][N];

int prim(){
    int mst[N], low[N], ans = 0;
    mst[1] = 0;
    for(int i = 2; i <= n; i++){
        low[i] = a[1][i];
        mst[i] = 1;
    }
    for(int i = 2; i <= n; i++){
        int minx = Inf, minid;
        for(int j = 2; j <= n; j++){
            if(low[j] < minx && low[j]){
                minid = j;
                minx = low[j];
            }
        }
        ans += minx;
        low[minid] = 0;
        for(int j = 2; j <= n; j++){
            if(a[minid][j] < low[j]){
                low[j] = a[minid][j];
                mst[j] = minid;
            }
        }
    }
    return ans;
}

int main(){
    while(scanf("%d%d", &n, &m) == 2){
        for(int i = 1; i <= n; i++){
            for(int j = 1; j <= n; j++){
                a[i][j] = Inf;
            }
        }
        for(int i = 0; i < m; i++){
            int u, v, w;
            scanf("%d%d%d", &u, &v, &w);
            a[u][v] = a[v][u] = w;
        }
        printf("%d\n", prim());
    }
}
/*
6 10  
1 2 6  
1 3 1  
1 4 5  
2 3 5  
2 5 3  
3 4 5  
3 5 6  
3 6 4  
4 6 2  
5 6 6  
*/