hdu1162 Eddy's picture (prim最小生成树)

来源：互联网发布：python编辑器知乎编辑：程序博客网时间：2024/05/18 00:06

#include <cstdio>#include <iostream>#include <algorithm>#include <cmath>#define INF 1000000.0#define MAXN 102using namespace std;//最小生成树double map[MAXN][MAXN],dist[MAXN];double px[MAXN],py[MAXN];int visited[MAXN];double distans(double x1,double x2,double y1,double y2){return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));}double prim(int n){int i,j,u;double min,sum=0.0;for (i=1;i<=n;i++){dist[i]=map[1][i];visited[i]=0;}visited[1]=1;dist[1]=0.0;for (i=2;i<=n;i++){min=INF;u=1;for(j=1;j<=n;j++)if(!visited[j]&&dist[j]<min){min=dist[j];u=j;}visited[u]=1;sum+=min;for(j=1;j<=n;j++)if(!visited[j]&&dist[j]>map[u][j])dist[j]=map[u][j];}return sum;}int main(){int n,i,j;double ans;while(scanf("%d",&n)!=EOF){for(i=1;i<=n;i++)scanf("%lf %lf",&px[i],&py[i]);for (i=1;i<=n;i++){for (j=i;j<=n;j++){map[i][j]=map[j][i]=distans(px[i],px[j],py[i],py[j]);}}ans=prim(n);printf("%.2lf\n",ans);}return 0;}