java - 从 val : Can't import anything other than java. util.Arrays 返回最远的 K

Question

需要返回k个元素a[i]，使得ABS(a[i] - val)是第k个最大的评估。我的代码仅适用于大于 val 的整数。如果整数小于 val，它将失败。我可以在不导入 java.util.Arrays 以外的任何内容的情况下执行此操作吗？任何帮助将不胜感激!

import java.util.Arrays;

public final class Selector {

private Selector() {
 } 
public static int[] farthestK(int[] a, int val, int k) {// This line should not change                  
  int[] b = new int[a.length];
  for (int i = 0; i < b.length; i++) {
     b[i] = Math.abs(a[i] - val);
  }
  Arrays.sort(b);
  int[] c = new int[k];
  int w = 0;
  for (int i = b.length-1; i > b.length-k-1; i--) {       
     c[w] = b[i] + val;
     w++;     
  }
  return c;    
}

测试用例:

import org.junit.Assert;
import static org.junit.Assert.*;
import org.junit.Before;
import org.junit.Test;


public class SelectorTest {


 /** Fixture initialization (common initialization
  *  for all tests). **/
 @Before public void setUp() {
 }
  @Test public void farthestKTest() {
       int[] a = {-2, 4, -6, 7, 8, 13, 15};
       int[] expected = {15, -6, 13, -2};
       int[] actual = Selector.farthestK(a, 4, 4);
       Assert.assertArrayEquals(expected, actual);
     }
 }

 There was 1 failure:
 1) farthestKTest(SelectorTest)
 arrays first differed at element [1]; expected:<-6> but was:<13>
 FAILURES!!!
 Tests run: 1,  Failures: 1

Answer 1

通过将距离存储为绝对值，您将破坏最后一个 for 循环，该循环根据绝对值重新计算原始值。

使用一个比较器，它使用abs值进行比较，但将数组值与搜索值的差值存储在数组b中怎么样？

这里会是这样的:

public static int[] farthestK(int[] a, int val, int k) {// This line should not change
    Integer[] b = new Integer[a.length];
    for (int i = 0; i < b.length; i++) {
      b[i] = a[i] - val;
    }
    Arrays.sort(b, new Comparator<Integer>() {

      @Override
      public int compare(Integer arg0, Integer arg1) {
        return Integer.valueOf(Math.abs(arg0)).compareTo(Math.abs(arg1));
      }
    });
    int[] c = new int[k];
    int w = 0;
    for (int i = b.length - 1; i > b.length - k - 1; i--) {
      c[w] = b[i] + val;
      w++;
    }
    return c;
  }