uva 10803 - Thunder Mountain

//floyd算法

//floyd算法描述:1.它是基于动规的

//                     2.它是基于如下特点的:设k是i->j的中间点.那么:(1)如果从i到j的最短路径中不包含点k,则i->j的最短路径的点由1~(k-1)

//                                                                                          的点组成.

//                                                                                      (2)如果含k点,那么我们一定能用k点进行Relax().

//即下图的递推关系:

 

 

 

 

#include <iostream>#include <cstdio>#include <cmath>#include <memory.h>#define epsilon 1e-5using namespace std;const int MAX =1025 ;const double INF =1<<20 ;int n,coo[105][2];double map[MAX][MAX],d[MAX][MAX];int compare(const double &i,const double &j){ double t=i-j; if(fabs(t)<epsilon) return 0;//0代表相等 else if(t<-epsilon) return -1;//1代表 i<j else return 1;//1代表 i>j}double dis(const int & i,const int &j){ double t=sqrt(pow((double)coo[i][0]-(double)coo[j][0],2)+ pow((double)coo[i][1]-(double)coo[j][1],2)); //cout<<i<<" "<<j<<" :"<<t<<endl; if(compare(t,10.0)==1) return INF; else return t;}int main(){ freopen("i.txt","r",stdin); int nCase,num=1; cin>>nCase; double maxVal; while(nCase--){ cout<<"Case #"<<num++<<":"<<endl; cin>>n; for(int i=0;i<n;++i) cin>>coo[i][0]>>coo[i][1]; maxVal=-INF; memset(map,0,sizeof(map)); for(int i=0;i<n;++i){ for(int j=i+1;j<n;++j){ map[i][j]=map[j][i]=dis(i,j); //d[i][j]=d[j][i]=INF; } } //for(int i=0;i<n;i++) // d[i][i]=0; for(int k=0;k<n;k++){ for(int i=0;i<n;i++){ for(int j=0;j<n;j++) if(map[i][j]>map[i][k]+map[k][j]) map[i][j]=map[i][k]+map[k][j]; } } for(int i=0;i<n;++i) for(int j=0;j<n;++j) if(maxVal<map[i][j]) maxVal=map[i][j]; if(maxVal==INF) cout<<"Send Kurdy"<<endl; else printf("%.4lf/n",maxVal); cout<<endl; /*for(int i=0;i<n;++i){ for(int j=0;j<n;++j){ cout<<map[i][j]<<" "; } cout<<endl; }*/ } return 0;}