TCHS-10-250

Problem Statement

    

Given a int[] x and a percentile p (between 0 and 100, inclusive), find the smallest element y in x such that at least p percent of the elements in x are less than or equal to y.

Definition

    
Class: Fractile
Method: fractile
Parameters: int[], int
Returns: int
Method signature: int fractile(int[] x, int p)
(be sure your method is public)
    
 

Constraints

- x will contain between 1 and 50 elements, inclusive.
- Each element of x will be between -1000000 and 1000000, inclusive.
- p will be between 0 and 100, inclusive.

Examples

0)  
    
{-3,-5,2,1}
 
50
 
Returns: -3
 
50 percent of the elements in x are less than or equal to -3: -5 and -3.
1)  
    
{7,9,2,-10,-6}
 
50
 
Returns: 2
 
60 percent of the elements in x are less than or equal to 2, and 40 percent are less than or equal to -6. At least 50% of the elements must be less than or equal to the answer, so the answer is 2.
2)  
    
{1,2,3,4,5,6,7,8,9,10}
 
39
 
Returns: 4
 
4 gives 40%, but 3 gives 30%, which is not enough, so 4 is the answer.
3)  
    
{1,2,3,4,5,6,7,8,9,1,2,3,4,5,7,9,5,43,124,94}
 
0
 
Returns: 1
 
The smallest element of x is 1 and it gives 5%.
4)  
    
{1}
 
100
 
Returns: 1
 
1 is the only element of x, so there is no choice at all.
import java.util.Arrays;

public class Fractile {

	public int fractile(int[] x, int p) {
		int k = (int) Math.ceil(p * x.length / 100.0);
		Arrays.sort(x);
		return (k > 0) ? x[k-1] : x[0];
	}

}

  

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