算法之归并排序
package com.ebiz.sort;import java.util.Arrays;/*** @author YHj* @create 2019-09-03 22:21* /*** 歸并排序(遞歸)** ①. 將序列每相鄰兩個數字進行歸并操作,形成 floor(n/2)個序列* ②. 執行①直到每組有一個元素
* ③. 各組之間進行比較* ④. 重復步驟③,直到所有元素排序完畢。*/public class Merge {public static void main(String[] args) {int [] arr = {8,4,5,7,1,3,6,2,9};mergingSort(arr);}public static int[] mergingSort(int[] arr){if(arr.length <= 1){return arr;}int num = arr.length >> 1;int[] leftArr = Arrays.copyOfRange(arr, 0, num);int[] rightArr = Arrays.copyOfRange(arr, num, arr.length);System.out.println("split two array: " + Arrays.toString(leftArr) + " And " + Arrays.toString(rightArr));return mergeTwoArray(mergingSort(leftArr), mergingSort(rightArr)); //不斷拆分為最小單元,再排序合并 }private static int[] mergeTwoArray(int[] arr1, int[] arr2){int i = 0, j = 0, k = 0;int[] result = new int[arr1.length + arr2.length]; //申請額外的空間存儲合并之后的數組while(i < arr1.length && j < arr2.length){ //選取兩個序列中的較小值放入新數組if(arr1[i] <= arr2[j]){result[k++] = arr1[i++];}else{result[k++] = arr2[j++];}}while(i < arr1.length){ //序列1中多余的元素移入新數組result[k++] = arr1[i++];}while(j < arr2.length){ //序列2中多余的元素移入新數組result[k++] = arr2[j++];}System.out.println("Merging: " + Arrays.toString(result));return result;}}
* ③. 各組之間進行比較* ④. 重復步驟③,直到所有元素排序完畢。*/public class Merge {public static void main(String[] args) {int [] arr = {8,4,5,7,1,3,6,2,9};mergingSort(arr);}public static int[] mergingSort(int[] arr){if(arr.length <= 1){return arr;}int num = arr.length >> 1;int[] leftArr = Arrays.copyOfRange(arr, 0, num);int[] rightArr = Arrays.copyOfRange(arr, num, arr.length);System.out.println("split two array: " + Arrays.toString(leftArr) + " And " + Arrays.toString(rightArr));return mergeTwoArray(mergingSort(leftArr), mergingSort(rightArr)); //不斷拆分為最小單元,再排序合并 }private static int[] mergeTwoArray(int[] arr1, int[] arr2){int i = 0, j = 0, k = 0;int[] result = new int[arr1.length + arr2.length]; //申請額外的空間存儲合并之后的數組while(i < arr1.length && j < arr2.length){ //選取兩個序列中的較小值放入新數組if(arr1[i] <= arr2[j]){result[k++] = arr1[i++];}else{result[k++] = arr2[j++];}}while(i < arr1.length){ //序列1中多余的元素移入新數組result[k++] = arr1[i++];}while(j < arr2.length){ //序列2中多余的元素移入新數組result[k++] = arr2[j++];}System.out.println("Merging: " + Arrays.toString(result));return result;}}
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轉載于:https://www.cnblogs.com/jiushixihuandaqingtian/p/11463263.html
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