最小生成树模板整理

来源：互联网发布：开源云计算平台数据库编辑：程序博客网时间：2024/05/22 13:04

以LUOGU 3366为测试例题（POJ挂了我能怎么办我也很绝望啊）

Kruskal 按秩并查集 AC

#include <cstdio>#include <iostream>#include <cstring>#include <algorithm>using namespace std;const int MAXN = 5000 + 10;const int MAXM = 200000 + 10;struct node { int u, v, cost; }edge[MAXM];int n, m, fa[MAXN], rank[MAXN];inline void init() { for(int i = 1; i <= n; ++i) fa[i] = i, rank[i] = 0; }inline bool cmp(node a, node b) { return a.cost < b.cost; }inline int find(int x) { return fa[x] == x ? x : fa[x] = find(fa[x]); }inline bool same(int a, int b) { return find(a) == find(b); }inline void unite(int x, int y) {    x = find(x), y = find(y);    if(x == y) return;    if(rank[x] < rank[y]) fa[x] = y;    else {        fa[y] = x;        if(rank[x] == rank[y]) rank[x]++;    }}inline int kruskal() {    sort(edge + 1, edge + m + 1, cmp);    init();    int res = 0;    for(int i = 1; i <= m; ++i) {        node e = edge[i];        if(!same(e.u, e.v)) {            unite(e.u, e.v);            res += e.cost;        }    }    return res;}int main() {    scanf("%d%d", &n, &m);    for(int i = 1, u, v, w; i <= m; ++i) {        scanf("%d%d%d", &u, &v, &w);        edge[i].u = u; edge[i].v = v; edge[i].cost = w;    }    int ans = kruskal(), tmp = find(1);    bool flag = false;    for(int i = 2; i <= n; ++i) if(find(i) != tmp) {        flag = true; break;    }    if(flag) puts("orz");    else printf("%d\n", ans);    return 0;}

~~想了想我还是不写Prim了学什么Prim啊会Kruskal你还想着Prim，你爱不爱她啊~~

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