[leecode]快速排序

package test
 
object QuickSort {
 
  def quickSort(arr:Array[Int],startIndex:Int,endIndex:Int):Unit={
    if(startIndex>=endIndex) return
    //递归结束条件：startIndex>=endIndex
    val pivotIndex:Int=partition(arr,startIndex,endIndex); //得到基准元素应该在的位置
    quickSort(arr,startIndex,pivotIndex-1);//根据基准元素，分成两部分进行递归排序
    quickSort(arr,pivotIndex+1,endIndex)
  }
 
  //进行一次排序
  def partition(arr: Array[Int], startIndex: Int, endIndex: Int): Int ={
    val pivot:Int=arr(startIndex) //基准元素
    var left:Int=startIndex
    var right:Int=endIndex
 
    while(left!=right){
      while(left=pivot) right=right-1 //控制right指针比较并左移
      while(left1 //控制left指针比较并右移
      if(leftval p=arr(left);arr(left)=arr(right);arr(right)=p} //左右交换
    }
 
    arr(startIndex)=arr(left) //将基准元素和中间位置进行交换
    arr(left)=pivot
 
    left
  }
 
  def main(args: Array[String]): Unit = {
    val arr:Array[Int]=Array(4,4,6,5,3,2)
    quickSort(arr,0,arr.length-1)
    println(arr.mkString(" "))
  }
}