归并排序及其kotlin实现

Posted 2021-01-07 jason31

归并排序的基本原理是，先将一个数组递归地二分，然后在分到一定程度之后将它们重新组合，并且在组合的过程中按顺序排列，达到排序的目的。

 

import java.util.*

fun merge(a:Array<Int>, low:Int, mid:Int, high:Int){
    var temp = IntArray(high-low+1)
    var i:Int = low
    var j:Int = mid + 1
    var k:Int = 0
　　//合并过程
    while( i<= mid && j<= high){
        temp[k++] = if(a[i]< a[j]) a[i++] else a[j++]
    }
    while(i<= mid) temp[k++] = a[i++]
    while(j<= high) temp[k++] = a[j++]
    for(k2 in temp.indices) a[k2+ low] = temp[k2]
}

fun mergeSort(a:Array<Int>, low:Int, high:Int){
    var mid:Int = (low+ high)/ 2
    if( low< high){
        mergeSort(a, low, mid)
        mergeSort(a, mid+1, high)
        merge(a, low, mid, high)
    }
}

fun main(args:Array<String>){
    var a = arrayOf(37, 26, 12, 8, 63, 5, 9, 57, 60)
    mergeSort(a, 0, a.size-1)
    println("结果：${Arrays.toString(a)}")
}