将两个数组合并为一个按升序无法正常工作的数组。 Java的

Question

I am trying to sort two arrays into one array. But I am having a few problems. it's not sorting correctly. I have attached the files, code and the output.

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Arrays;
import java.util.Scanner;

public class MArray {


public static void mergeA(long[] A, long[] B) {

long [] merged = new long[A.length + B.length ];
int indexFirst = 0, indexSecond = 0, indexMerge = 0;

while (indexFirst < A.length && indexSecond < B.length) {
    if (A[indexFirst] <= B[indexSecond]) {
        merged[indexMerge++] = A[indexFirst++];
    }
    else {           
        merged[indexMerge++] = B[indexSecond++];
    }
}


    System.out.print("\n");
    System.out.println("Here is your merged array: " );

    for (int i = 0; i < merged.length; i++) {
       System.out.print(merged[i] + ", ");
    }


}

public static void main(String[] args) throws FileNotFoundException {
    // TODO Auto-generated method stub

    long array1[] = null;
    long array2[] = null;


    Scanner Scanscan = new Scanner(System.in);
    System.out.print("Input filename: ");
    String filename = Scanscan.nextLine();
    File inputFile = new File(filename);
    Scanner reader = new Scanner(inputFile);

    int i = 0;
    long array[] = new long[20];
    while(reader.hasNext())
    {
        array[i] = reader.nextInt();
        i++;

    }
    array1 = new long[i];
    System.arraycopy(array, 0, array1, 0, i);
    Arrays.sort(array1);

    for (int i1 = 0; i1 < array1.length; i1++) {
           System.out.print(array1[i1] + " ");
        }



    System.out.println( "\n");


    System.out.println("Please enter your second file name: ");

    String filename2 = Scanscan.nextLine();
    File inputFile2 = new File(filename2);
    Scanner reader2 = new Scanner(inputFile2);

      int i1 = 0;
        long temp1[] = new long[20];
        while(reader2.hasNext())
        {
            temp1[i1] = reader2.nextInt();
            i1++;

        }
        array2 = new long[i1];
        System.arraycopy(temp1, 0, array2, 0, i1);
        Arrays.sort(array2);

        for (int i11 = 0; i11 < array2.length; i11++) {
               System.out.print(array2[i11] + " ");
            }



    mergeA(array1, array2);


}

}

input 1 2 4 6 8 10

input 2 12 14 16 18 20 22 24

output Input filename: input1_1.txt 2 4 6 8 10

Please enter your second file name: 
input1_2.txt
   12 14 16 18 20 22 24 
Here is your merged array: 
2, 4, 6, 8, 10, 0, 0, 0, 0, 0, 0, 0,

Answer 1

If you really have the requirement of having un-sorted arrays as potential input, you could use Merge Sort to sort the two individual arrays, and then do one last Merge operation to join the two sorted arrays.

Here is a test run with your initial non-sorted input:

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Arrays;
import java.util.Scanner;

public class MArray {

  public static void mergeA(long[] A, long[] B) {

    long [] merged = new long[A.length + B.length ];
    int indexFirst = 0, indexSecond = 0, indexMerge = 0;

    while (indexFirst < A.length && indexSecond < B.length) {
        if (A[indexFirst] <= B[indexSecond]) {
            merged[indexMerge++] = A[indexFirst++];
        }
        else {           
            merged[indexMerge++] = B[indexSecond++];
        }
    }

    //get remaining items if arrays were not equal lengths

    while (indexFirst < A.length){
       merged[indexMerge++] = A[indexFirst++];
    }

    while (indexSecond < B.length){
       merged[indexMerge++] = B[indexSecond++];
    }


    System.out.print("\n");
    System.out.println("Here is your merged array: " );

    for (int i = 0; i < merged.length; i++) {
      System.out.print(merged[i] + ", ");
    }


  }

  public static void main(String[] args) throws FileNotFoundException {
      // TODO Auto-generated method stub

      long array1[] = null;
      long array2[] = null;

  /*
      Scanner Scanscan = new Scanner(System.in);
      System.out.print("Input filename: ");
      String filename = Scanscan.nextLine();
      File inputFile = new File(filename);
      Scanner reader = new Scanner(inputFile);

      int i = 0;
      while(reader.hasNextInt())
      {
           array1[i++] = reader.nextInt();
      }

      for (int i1 = 0; i1 < array1.length; i1++) {
             System.out.print(array1[i1] + " ");
          }
      System.out.println( "\n");


      System.out.println("Please enter your second file name: ");

      String filename2 = Scanscan.nextLine();
      File inputFile2 = new File(filename2);
      Scanner reader2 = new Scanner(inputFile2);

      int i1 = 0;

      while(reader2.hasNextInt()){
         array2[i1++] = reader2.nextInt();
      }
       System.out.println("  ");

       for (int i11 = 0; i11 < array2.leng= th; i11++) {
             System.out.print(array2[i11] + " ");
          }
          */


    long[] a1 = new long[]{1, 9, 6, 11, 12, 4, 7, 2};
    long[] a2 = new long[]{2, 8, 3, 13, 5, 10};

    mergeSort(a1);
    mergeSort(a2);

    array1 = new long[a1.length];
    System.arraycopy(a1, 0, array1, 0, a1.length);

    array2 = new long[a2.length];
    System.arraycopy(a2, 0, array2, 0, a2.length);

    mergeA(array1, array2);

  }

  static void mergeSort(long[] array){
    long[] helper = new long[array.length];
    mergeSort(array, helper, 0, array.length - 1);
  }

  static void mergeSort(long[] array, long[] helper, int low, int high){
    if (low < high){
      int middle = (low + high) / 2;
      mergeSort(array, helper, low, middle);
      mergeSort(array, helper, middle + 1, high);
      merge(array, helper, low, middle, high);
    }
  }

  static void merge(long[] array, long[] helper, int low, int middle, int high){
    for (int i = low; i <= high; i++){
      helper[i] = array[i];
    }

    int helperLeft = low;
    int helperRight = middle + 1;
    int current = low;
    while (helperLeft <= middle && helperRight <= high){
      if (helper[helperLeft] <= helper[helperRight]){
        array[current++] = helper[helperLeft++];
      }
      else{
        array[current++] = helper[helperRight++];
      }
    }
    while (helperLeft <= middle){
      array[current++] = helper[helperLeft++];
    }
  }


}

Output:

Here is your merged array: 
1, 2, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,