hdu 1233 最小生成树kruskal版

        kruskal算法就是在并查集基础上加了个贪心，算法正确性的证明看完算法导论自己还不怎么懂，不过感觉写走来比起prim要来得顺手得多

#include<iostream>#include<vector>#include<algorithm>using namespace std;class node{public:int x;int y;int dis;};bool cmp(node& lhs,node& rhs){return lhs.dis < rhs.dis;}int n;vector<node> way;vector<int> father;int find_father(int x){if(x == father[x])return x;else{father[x] = find_father(father[x]);//压缩路径}return father[x];}void merge(int a,int b){father[a] = b;}int Mst_kruskal(){int res = 0;sort(way.begin(),way.end(),cmp);//贪心排序int temp = n*(n-1)/2;for(int i = 0;i <= n;i++){//初始化父结点father.push_back(i);}for(int i = 0;i < temp;i++){int fx = find_father(way[i].x);int fy = find_father(way[i].y);if(fx != fy){res += way[i].dis;merge(fx,fy);}}return res;}int main(){while(scanf("%d",&n)==1 && n){int temp = n*(n-1)/2;for(int i = 0;i < temp;i++){node a;scanf("%d %d %d",&a.x,&a.y,&a.dis);way.push_back(a);}printf("%d\n",Mst_kruskal());way.clear();//注意清空father.clear();}return 0;}