[hoj 1632]Jungle Roads[Kruskal最小生成树模板题]

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题意:

求最小生成树的边长和.

#include <cstdio>#include <vector>#include <algorithm>using namespace std;const int MAXN = 30;int f[MAXN];int n;typedef struct edge{    int u,v,w;    edge(){}    edge(int _u, int _v, int _w):u(_u),v(_v),w(_w){}}edge;vector<edge> g;bool cmp(edge a, edge b){    return a.w<b.w;}int find_set(int x){    if(f[x]!=x)        f[x] = find_set(f[x]);    return f[x];}int Kruskal(){    sort(g.begin(),g.end(),cmp);    for(int i=0;i<n;i++)    f[i] = i;    int ans = 0;    for(int i=0;i<g.size();i++)    {        int u = g[i].u, v = g[i].v;        u = find_set(u), v = find_set(v);        if(u==v)    continue;        f[u] = v;        ans += g[i].w;    }    return ans;}int main(){    while(scanf("%d",&n)==1 && n)    {        g.clear();        for(int i=0,m;i<n-1;i++)        {            char c;            scanf(" %c %d",&c,&m);            for(int j=0,w;j<m;j++)            {                scanf(" %c %d",&c,&w);                g.push_back(edge(i, c-'A', w));            }        }        printf("%d\n",Kruskal());    }}