kruskal

typedef struct s {
	int a, b;
	int weight;
}Edge;

void kruskal(Graph G, Edge* e, int* parent) {
	sort(e);   //按边的权值进行排序
	init(parent);  //初始化并查集

	for (int i = 0; i < G.num; i++) {
		int a_root = find(parent, e[i].a);
		int b_root = find(parent, e[i].b);
		if (a_root != b_root) unite(parent, a_root, b_root); //若a,b没在一个集合，则进行合并
	}
}

prim

#include<bits/stdc++.h>

using namespace std;
const int maxn = 105, inf = 1 << 30;

int map[maxn][maxn];
int visit[maxn]; //
int d[maxn];  //当前到已选节点到未选节点的最小距离

int prim() {
	int ans = 0;

	for(int i = 0; i < maxn; i++) {
		visit[i] = 0;
		d[maxn] = inf;
	}

	d[1] = 0;
	visit[1] = 1;

	while (1) {
		int v = -1;
		for (int i = 1; i <= n; i++) {
			if (!visit[i] && (v == -1 || d[i] < d[v])) v = i; //
		}
		if (v == -1) break;   //访问完了，退出
		visit[v] = 1;
		if (d[v] == inf) return -1;  //孤立节点
		ans += d[v];

		for (int i = 1; i <= n; i++) {
			if (!visit[i]) d[i] = min(d[i], map[v][i]);
		}
			
	}
	return ans;

	
}