Minimum spanning tree-Kruskal algorithm

  Not to mention the concept of minimum spanning tree, this article mainly implements Kruskal's algorithm, and uses the idea of ​​union search. Compared with the prim algorithm, Kruskal is easier to understand: in the case of not forming a ring, the smallest weight edge is selected until the number of points is reduced by one. For the judgment of the ring, the idea of ​​consolidating and collecting is used. This article gives a template:

#include<bits/stdc++.h>
using namespace std;
const int max_one = 1000;
struct node {
    
    
	int u, v, w; // u, v代表边，w代表权值
}bian[max_one];

static bool cmp(node a, node b) {
    
    
	return a.w < b.w;
}

int find(int x) {
    
    
	if (x == a[x])
		return x;
	else
		return a[x]=find(a[x]); // 使用这种形式，不要return find(a[x]),减少重复递归
}
int a[max_one]; // a数组就是存储并查集每一个节点父节点

int main(void) {
    
    
	// 假设有n个点，m条边
	for (int i=1; i<=n; i++) {
    
    
		a[i] = i; // 初始化并查集数组为自身
	}
	输入m条对应边及权值
	sort(bian+1, bian+1+m, cmp); // 对权值进行排序，自定义cmp函数
	int ans = 0;
	int bian_num = 0;
	for (int i=1; i<=m && bian_num != n-1; i++) {
    
    
		int u = bian[i].u;
		int v = bian[i].v;
		int w = bian[i].w;
		int fu = find(u);
		int fv = find(v);
		if (fu == fv)
			continue;
		a[fv] = fu;
		ans += w;
		bian_num++;
	}
	cout << ans << endl; // ans即为最小权值
	return 0;
}

Reference materials:
https://blog.csdn.net/uestct/article/details/47282191
https://blog.csdn.net/qq_40772692/article/details/79667455

Due to the limited level of the author, if there is any mistake, please point it out in the comment section below, thank you!