知识概览

• 克鲁斯卡尔算法适用于稀疏图求最小生成树，时间复杂度为O(mlogm)。

例题展示

题目链接

Kruskal算法求最小生成树

859. Kruskal算法求最小生成树 - AcWing题库https://www.acwing.com/problem/content/861/

代码

#include <iostream>
#include <algorithm>using namespace std;const int N = 200010;int n, m;
int p[N];struct Edge 
{int a, b, w;bool operator < (const Edge &W) const{return w < W.w;}
} edges[N];int find(int x)
{if (p[x] != x) p[x] = find(p[x]);return p[x];
}int main()
{scanf("%d%d", &n, &m);for (int i = 0; i < m; i++){int a, b, w;scanf("%d%d%d", &a, &b, &w);edges[i] = {a, b, w};}sort(edges, edges + m);for (int i = 1; i <= n; i++) p[i] = i;int res = 0, cnt = 0;for (int i = 0; i < m; i++){int a = edges[i].a, b = edges[i].b, w = edges[i].w;a = find(a), b = find(b);if (a != b){p[a] = b;res += w;cnt++;}}if (cnt < n - 1) puts("impossible");else printf("%d\n", res);return 0;
}

参考资料

1. AcWing算法基础课