hdu 1875

prim算法，用double，我第一次用float wa，看了别人代码改成double就过了。

#include<stdio.h>#include<math.h>#define N 110#define max 9999999double g[N][N];void prim(int n){int i,j,u,flag,mark[N];double dis[N],cost,min;for(i=0;i<n;i++){mark[i]=0;dis[i]=g[0][i];}mark[0]=1;cost=0;flag=1;for(i=1;i<n;i++){min=max;for(j=1;j<n;j++)if(!mark[j]&&min>dis[j]){u=j;min=dis[j];}if(min==max||min<10){flag=0;break;}mark[u]=1;cost+=min;for(j=1;j<n;j++)if(!mark[j]&&dis[j]>g[u][j])dis[j]=g[u][j];}if(flag)printf("%.1f/n",100*cost);elseprintf("oh!/n");}int main(){int i,j,m,n,x[N],y[N];double dis,x2,y2;scanf("%d",&m);while(m--){scanf("%d",&n);for(i=0;i<n;i++)scanf("%d%d",&x[i],&y[i]);for(i=0;i<n;i++)for(j=0;j<=i;j++){x2=(x[i]-x[j])*(x[i]-x[j]);y2=(y[i]-y[j])*(y[i]-y[j]);dis=sqrt(x2+y2);if(dis<10||dis>1000)g[j][i]=g[i][j]=max;elseg[i][j]=g[j][i]=dis;}prim(n);}return 0;}