POJ 1251Jungle Roads（Kruskal）

来源：互联网发布：金十数据dora是谁编辑：程序博客网时间：2024/05/21 09:23

传送门：http://poj.org/problem?id=1251

题目没怎么看懂，反正是最小生成树题，感觉挺好过的。

#include<cstdio>#include<algorithm>#include<cmath>#include<vector>#include<iostream>#include<cstring>#include<stack>using namespace std;struct node{int s,e;int v;node(int a,int b,int c):s(a),e(b),v(c){}};bool cmp(node a,node b){return a.v<b.v;}vector<node> edge;int pre[110];int Find(int x){int s;for(s=x;pre[s]>=0;s=pre[s]);while(s!=x){int t=pre[x];pre[x]=s;x=t;}return s;}void join(int a,int b){int fa=Find(a),fb=Find(b);int sum=pre[fa]+pre[fb];if(pre[fa]>pre[fb]){pre[fa]=fb;pre[fb]=sum;}else{pre[fb]=fa;pre[fa]=sum;}}int kruskal(int n){int ans=0;int i;int cnt=0;for(i=0;i<edge.size();i++){if(Find(edge[i].s)!=Find(edge[i].e)){join(edge[i].s,edge[i].e);cnt++;ans+=edge[i].v;}if(cnt==n-1)break;}return ans;}int main(){int n;while(scanf("%d",&n)!=EOF&&n){edge.clear();memset(pre,-1,sizeof(pre));int i,j;for(i=1;i<n;i++){char op[2];int num;scanf("%s%d",op,&num);while(num--){char to[2];int vv;scanf("%s%d",to,&vv);edge.push_back(node(op[0]-'A',to[0]-'A',vv));}}sort(edge.begin(),edge.end(),cmp);printf("%d\n",kruskal(n));}return 0;}

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