java实现的一个【快速排序 】算法【原创】详解编程语言

import java.util.Arrays; 
import org.apache.commons.lang.ArrayUtils; 
 
public class Test { 
 
  public static void main(String[] args) { 
    int[] sortedArrays = quickSort(new int[]{3, 5, 1, 2}); 
    System.out.println(ArrayUtils.toString(sortedArrays)); 
  } 
 
  /** 
   * Run time is O(nlogn) 
   * 
   * @param source source array 
   * @return sorted array 
   */ 
  private static int[] quickSort(int[] source) { 
 
    int sourceSize = source.length; 
 
    final byte baseLen = 2; 
 
    // An array that is empty or contains only one element is ordered 
    if (sourceSize < baseLen) { 
      return source; 
    } 
 
    // pivot value 
    int pivotVal = source[sourceSize / 2]; 
 
    return combineList(quickSort(sortLeft(source, pivotVal)), pivotVal, quickSort(sortRight(source, pivotVal))); 
  } 
 
  private static int[] sortLeft(int[] source, int pivotVal) { 
    return sort(source, pivotVal, true); 
  } 
 
  private static int[] sortRight(int[] source, int pivotVal) { 
    return sort(source, pivotVal, false); 
  } 
 
  private static int[] sort(int[] source, int pivotVal, boolean isLeft) { 
    int[] subArray = new int[source.length - 1]; 
    int j = 0; 
    for (int value : source) { 
      boolean condition = isLeft && value < pivotVal || !isLeft && value > pivotVal; 
      if (condition) { 
        subArray[j++] = value; 
      } 
    } 
    return Arrays.copyOf(subArray, j); 
  } 
 
  private static int[] combineList(int[] less, int pivotVal, int[] greater) { 
    int[] a1 = ArrayUtils.add(less, pivotVal); 
    return ArrayUtils.addAll(a1, greater); 
  } 
 
}