MST算法

Kruskal

#include<bits/stdc++.h>
using namespace std;
#define INF 0x3f3f3f3f
#define M(a, b) memset(a, b, sizeof(a))
const int N = 1e3 + 10, maxn = 1e4 + 10;
int p[N], n, m;
struct Edge {
    int u, v, w;
    bool operator < (const Edge rhs) const {
        return w < rhs.w;
    }
}e[maxn];

int find(int u) {return u == p[u] ? u : find(p[u]);};

int Kruskal() {
    int ans = 0;
    for (int i = 0; i < n; ++i) p[i] = i;
    sort(e, e+m);
    for (int i = 0; i < m; ++i) {
        int u = find(e[i].u), v = find(e[i].v);
        if (u != v) {
            p[v] = u;
            ans += e[i].w;
        }
    }
    return ans;
}

Prim

#include<bits/stdc++.h>
using namespace std;
const int N = 1e4 + 5;
bool vis[N];
int n, m;
struct Node {
    int v, w;
    bool operator < (const Node &rhs) const {
        return w > rhs.w;
    }
};
vector<Node> G[N];

int Prim() {
    int ans = 0;
    M(vis, 0); vis[1] = 1;
    priority_queue<Node> q;
    q.push(Node{1, 0});
    int u = 1;
    for (int k = 1; k < n; ++k) {
        for (int i = 0; i < G[u].size(); ++i)
            if (!vis[G[u][i].v]) q.push(G[u][i]);
        while (!q.empty() && vis[q.top().v]) q.pop();
        ans += q.top().w;
        vis[q.top().v] = 1;
        u = q.top().v;
        q.pop();
    }
    return ans;
}