Pat Advanced 1089. Insert or Merge (25), 同Basic 1035. 插入与归并(25)

注意点：

这里的归并排序（Merge Sort），需要按照题意要求去归并。

题意：

归并排序进行如下迭代操作：先将原始序列看成N个只包含1个元素的有序子序列，

                                    然后每次迭代归并两个相邻的有序子序列，

                                    直到最后只剩下1个有序的序列。

Merge sort works as follows: Divide the unsorted list into N sublists, 

                                         each containing 1 element (a list of 1 element is considered sorted). 

                                         Then repeatedly merge two adjacent sublists to produce new sorted sublists 

                                         until there is only 1 sublist remaining.

思路：

        方法一：直观的解法，分别写出 Insert Sort 和Merge Sort，然后比较每一次迭代后的顺序，判断并输出；

        方法二：理解插入和归并排序，利用标准模版库中的 Sort 函数，有序地一轮一轮 Sort 数组，来模拟插入和归并每轮的输出。

方法一：Java代码

import java.util.Scanner;public class Main{static int arrLen;static int[] unSorted4Insert = new int[101];static int[] unSorted4Merge = new int[101];static int[] temp = new int[101];static String lineToJudge;static boolean onceMoreFlag=false;static boolean isMerge =false;static boolean isInsert=false;//{3,1,2,8}public static void insertSort02(){for(int i=1;i<arrLen;i++){if(unSorted4Insert[i]<unSorted4Insert[i-1]){int temp =unSorted4Insert[i];int j=i-1;while(j>=0 && unSorted4Insert[j]>temp){  unSorted4Insert[j+1]=unSorted4Insert[j];  j--;}unSorted4Insert[j+1]=temp;}if(onceMoreFlag){break;}StringBuilder sb =new StringBuilder();for(int f=0;f<arrLen;f++){sb.append(unSorted4Insert[f]+" ");}if(sb.toString().trim().equals(lineToJudge)){isInsert=true;onceMoreFlag=true;}}}public static void merge02(int start01,int end01,int start02,int end02){int start1 =start01;int end1   =end01;int start2 =start02;int end2   =end02;int i=start01;while(start1<=end1 && start2<=end2){if(unSorted4Merge[start1]<=unSorted4Merge[start2]){temp[i]=unSorted4Merge[start1];i++;start1++;}else{temp[i]=unSorted4Merge[start2];i++;start2++;}}while(start1<=end1){temp[i]=unSorted4Merge[start1];i++;start1++;}while(start2<=end2){temp[i]=unSorted4Merge[start2];i++;start2++;}for(int f=start01;f<=end02;f++){unSorted4Merge[f]=temp[f];}}public static void mergeSort02(int start,int end){for(int mergeStepLen=2   ;mergeStepLen/2<arrLen;mergeStepLen*=2){for(int i=0 ;i<arrLen ;i+=mergeStepLen){int start1=i;int end1  =i+mergeStepLen/2-1;//下标和长度相差1int start2=end1+1;if(start2>=arrLen){break;}int a=i+mergeStepLen-1;int b=arrLen-1;int end2  =a<b?a:b;merge02(start1,end1,start2,end2);}if(onceMoreFlag){break;}StringBuilder sb =new StringBuilder();for(int f=0;f<arrLen;f++){sb.append(unSorted4Merge[f]+" ");}if(sb.toString().trim().equals(lineToJudge)){isMerge=true;onceMoreFlag=true;}}}public static void main(String[] args) {Scanner sc =new Scanner(System.in);arrLen =sc.nextInt();for(int i =0;i<arrLen;i++){unSorted4Insert[i]=sc.nextInt();unSorted4Merge[i]=unSorted4Insert[i];}StringBuilder sb =new StringBuilder();for(int i =0;i<arrLen;i++){sb.append(sc.nextInt()+" ");}lineToJudge = sb.toString().trim();insertSort02();if(isInsert){System.out.println("Insertion Sort");sb.setLength(0);for(int f=0;f<arrLen;f++){sb.append(unSorted4Insert[f]+" ");}System.out.print(sb.toString().trim());}else{mergeSort02(0,arrLen-1);System.out.println("Merge Sort");sb.setLength(0);for(int f=0;f<arrLen;f++){sb.append(unSorted4Merge[f]+" ");}System.out.print(sb.toString().trim());}}}

【参考博客】

         【方法一】：直接写出Insert Sort 和 Merge Sort

         http://www.cnblogs.com/GoFly/p/4297485.html

         【方法二】：利用标准模版库提供的Sort 函数，模拟一轮一轮的Insert Sort 和 Merge Sort

        http://blog.csdn.net/cstopcoder/article/details/42567287

        http://tech.bingfengsa.com/a/20141201/39766.html