hdu4463-Outlets

http://acm.hdu.edu.cn/showproblem.php?pid=4463

// File Name: hdu4463.cpp// Author: bo_jwolf// Created Time: Thursday, May 09, 2013 PM01:06:34 HKT#include<vector>#include<list>#include<map>#include<set>#include<deque>#include<stack>#include<queue>#include<bitset>#include<algorithm>#include<functional>#include<numeric>#include<utility>#include<sstream>#include<iostream>#include<iomanip>#include<cstdio>#include<cmath>#include<cstdlib>#include<cstring>#include<ctime>using namespace std;const int maxn = 10005 ;int mapp[ 105 ][ 105 ] ;int fa[ maxn ] ;struct node{int x , y ;double dis ;}edge[ maxn ] ;struct Point{double xi , yi ;}point[ maxn ] ;int cmp( node a , node b ){return a.dis < b.dis ;}double  point_dis( Point a ,Point b ){return sqrt( ( a.xi - b.xi ) * ( a.xi - b.xi ) + ( a.yi -b.yi ) * ( a.yi - b.yi )  ) ;}int find( int x ){return fa[ x ] = x==fa[ x ] ? x : find( fa[ x ] ) ;}int main(){int n ;while( scanf( "%d" , &n ) != EOF && n ){int p , q;scanf( "%d%d" , &p , &q );//memset( fa , 0 , sizeof( fa ) ) ;for( int i = 0 ; i < maxn ; i++ )fa[ i ] = i ;for( int i = 1 ; i <= n ; i++ )scanf( "%lf%lf" , &point[i].xi , &point[i].yi ) ;int k = 0 ;for( int i = 1 ; i <= n ; i++ )for( int j = i + 1 ; j <= n ; j++ ){edge[ k ].x = i ;edge[ k ].y = j ;edge[ k ].dis = point_dis( point[ i ] , point[ j ] ) ;if( ( i ==  p && j == q ) || ( i == q && j == p ) )edge[ k ].dis = 0 ;k++;}sort( edge , edge + k , cmp ) ;double ans =  point_dis( point[ p ] , point [ q ] );int sum = 0;for( int i = 0 ; i <= k ; i++ ){int x1 = find ( edge[ i ].x );int x2 = find ( edge[ i ].y );if( x1 != x2 ){fa[ x1 ] = x2 ;ans += edge[ i ].dis ;sum++ ;if( sum == n - 1)break;}}printf( "%.2lf\n" , ans ) ;}return 0;}