Scala练习-基数排序

package day14

import scala.collection.mutable.ArrayBuffer

/**
* Created by doctorq on 2017/6/29.
* 基数排序
*/
object RadixSort extends Utils with App {

/*
获取数组中最大值
*/
def max(unSort: Array[Int]): Int = {
if (unSort.size < 1) throw new IllegalArgumentException
var temp = unSort(0)
for (i <- 1 until unSort.size) {
if (unSort(i) > temp) {
temp = unSort(i)
}
}

temp
}

/**
* 获取数字的位数
*
* @param item
* @return
*/
def getDigit(item: Int): Int = {
var digit = 1
var temp = item / 10
while (temp > 0) {
digit += 1
temp /= 10
}
digit
}

/**
* 获取数字在第index位上的值，123第二位的值2，第一位为3，第三位为1
*
* @param item
* @param index
* @return
*/
def getNum(item: Int, index: Int): Int = {
if (index < 1) throw new IllegalArgumentException
//超出,自动补0
if (getDigit(item) < index) return 0
val itemStr = item.toString
itemStr.charAt(itemStr.size - index).toString.toInt
}

def generate(num: Int): Array[ArrayBuffer[Int]] = {
val bucket = new Array[ArrayBuffer[Int]](10)
for (i <- 0 until num) {
val temp = new ArrayBuffer[Int]()
bucket(i) = temp
}
bucket
}

/**
* 平铺二维数组到一维
*
* @param bucketArray
* @return
*/
def flatten(bucketArray: Array[ArrayBuffer[Int]], size: Int): Array[Int] = {
val temp = new Array[Int](size)
var index = 0
for (i <- 0 until bucketArray.size) {
if (bucketArray(i).size != 0) {
for (j <- 0 until bucketArray(i).size if (bucketArray(i)(j) >= 0)) {
temp(index) = bucketArray(i)(j)
index += 1
}
}
}
temp
}

/**
*
* @param unSort 原始数组
* @param digit  最大数的位数
* @return 已排序好的数组
*/
def sort(unSort: Array[Int], digit: Int): Array[Int] = {

var tempUnSort = unSort
for (i <- 1 to digit) {
val bucket = generate(10)
for (j <- 0 until tempUnSort.size) {
val index = getNum(tempUnSort(j), i)
bucket(index).append(tempUnSort(j))
}

tempUnSort = flatten(bucket, tempUnSort.size)
}

tempUnSort
}

val array = Array[Int](1, 45, 23, 0, 23, 234, 23, 5, 6, 7, 9, 9, 9, 456)
val digit = getDigit(max(array))
printlnArray(sort(array, digit))
}