传送门:【HDU】4932 Miaomiao's Geometry
题目分析:暴力啊。。。只要枚举两点间的长度,用这个长度或者这个长度的一半去填一下看行不行,可以就更新最大值,二分这个感觉是不能过的啊。。没有单调性吧。。。
附几组数据:
3
12
0 1 10 11 20 21 30 31 40 41 50 51
5
1 6 10 19 20
4
1 2 99 100
代码如下:
#include <map>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std ;
#define REP( i , a , b ) for ( int i = a ; i < b ; ++ i )
#define FOR( i , a , b ) for ( int i = a ; i <= b ; ++ i )
#define REV( i , a , b ) for ( int i = a ; i >= b ; -- i )
#define CLR( a , x ) memset ( a , x , sizeof a )
int a[60] , vis[60] ;
int n ;
int ok ( long long length ) {
CLR ( vis , 0 ) ;
int ok = 1 ;
vis[0] = 1 ;
REP ( i , 1 , n - 1 ) {
if ( vis[i] )
continue ;
if ( vis[i - 1] == 1 ) {
if ( a[i] - a[i - 1] >= length )
vis[i] = 1 ;
else if ( a[i + 1] - a[i] >= length ) {
vis[i] = 2 ;
if ( a[i + 1] - a[i] == length )
vis[i + 1] = 1 ;
} else
return 0 ;
} else {
if ( a[i] - a[i - 1] >= 2 * length )
vis[i] = 1 ;
else if ( a[i + 1] - a[i] >= length ) {
vis[i] = 2 ;
if ( a[i + 1] - a[i] == length )
vis[i + 1] = 1 ;
} else
return 0 ;
}
}
return 1 ;
}
void solve () {
scanf ( "%d" , &n ) ;
REP ( i , 0 , n )
scanf ( "%d" , &a[i] ) , a[i] *= 2 ;
sort ( a , a + n ) ;
long long mmax = 0 ;
REP ( _ , 1 , n ) {
long long length = a[_] - a[_ - 1] ;
if ( ok ( length ) )
mmax = max ( mmax , length ) ;
if ( ok ( length / 2 ) )
mmax = max ( mmax , length / 2 ) ;
}
printf ( "%.3f\n" , ( double ) mmax / 2 ) ;
}
int main () {
int T ;
scanf ( "%d" , &T ) ;
while ( T -- )
solve () ;
return 0 ;
}