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Implementation of the merge algorithm of merge sort

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John Maina answered on July 13, 2022 Popularity 1/10 Helpfulness 1/10

answer Implementation of the merge algorithm of merge sort

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Implementation of the merge algorithm of merge sort

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#L is the list while L1 and L2 are the sublists.

def merge(L1, L2, L):
  i = j = 0
  while i+j < len(L):
    if j == len(L2) or (i < len(L1) and L1[i] < L2[j]):
       L[i+j] = L1[i]
       i += 1

    else:
       L[i+j] = L2[j]
       j += 1

#example
L = [2, 7, 4, 0, 6, 5]
L1 = [2, 4, 7]
L2 = [0, 6, 5]

merge(L1, L2, L)
print(L)

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Source: www.pynerds.com

Tags: algorithm implementation merge python

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Contributed on Apr 15 2024

John Maina

0 Answers Avg Quality 2/10

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Merge In Mergesort

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Informal explanation of merge in merge sort
We have two arrays that are already sorted: one on the left and the other on the right
We stick them together (left+right array). 
We then compare the terms starting from the 0th([0] term for both left and right arrays.
So left[0] compare with right[0](or more correctly, array[0] with array[mid+1])
We create a blank array
If the left[0] term is bigger, we add left[0] to blank array as its first term. 
If the right[0] term is bigger, we add right[0] to the blank array as its first term.
Assuming left[0] is bigger, We then move to left[1] vs right[0].
We keep doing this until we run out of terms in one of the arrays. 
We then stick the remaining terms of the array where we didn't run out to the end of our (originally, now no longer) blank array. 
The blank array has now been sorted!

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Tags: merge merg

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Contributed on Jul 13 2022

Javasper

0 Answers Avg Quality 2/10

Merge sort algorithm

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import java.util.Random;

public class MergeSort {
  public static void main(String[] args) {

    Random rand = new Random();
    int[] numbers = new int[10];

    for (int i = 0; i < numbers.length; i++) {
      numbers[i] = rand.nextInt(1000000);
    }

    System.out.println("Before:");
    printArray(numbers);

    mergeSort(numbers); 

    System.out.println("\nAfter:");
    printArray(numbers);
  }


  private static void mergeSort(int[] inputArray) {
    int inputLength = inputArray.length;
    
    if (inputLength < 2) {
      return;
    }
    
    int midIndex = inputLength / 2;
    int[] leftHalf = new int[midIndex];
    int[] rightHalf = new int[inputLength - midIndex];
    
    for (int i = 0; i < midIndex; i++) {
      leftHalf[i] = inputArray[i];
    }
    for (int i = midIndex; i < inputLength; i++) {
      rightHalf[i - midIndex] = inputArray[i];
    }
    
    mergeSort(leftHalf);
    mergeSort(rightHalf);
    
    merge(inputArray, leftHalf, rightHalf);
  }

  private static void merge (int[] inputArray, int[] leftHalf, int[] rightHalf) {
    int leftSize = leftHalf.length;
    int rightSize = rightHalf.length;
    
    int i = 0, j = 0, k = 0;
    
    while (i < leftSize && j < rightSize) {
      if (leftHalf[i] <= rightHalf[j]) {
        inputArray[k] = leftHalf[i];
        i++;
      }
      else {
        inputArray[k] = rightHalf[j];
        j++;
      }
      k++;
    }
    
    while (i < leftSize) {
      inputArray[k] = leftHalf[i];
      i++;
      k++;
    }
    
    while (j < rightSize) {
      inputArray[k] = rightHalf[j];
      j++;
      k++;
    }
    
  }

  private static void printArray(int[] numbers) {
    for (int i = 0; i < numbers.length; i++) {
      System.out.println(numbers[i]);
    }
  }
}

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Source: Grepper

Tags: algorithm algo

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Contributed on Mar 12 2023

Awful Anaconda

0 Answers Avg Quality 2/10

merge sort algorithm

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int i =0,j=0,k=0;
    while(i<A.size() && B.size())
    {
        if(A[i] < B[j])
        {
            C[k++] = B[j++];
        }
        else
        {
            C[k++] = A[i++];
        }
    }
    while(i<A.size()){
        C[k++] = A[i++];
    }
    while(j<B.size())
    {
        C[k++] = B[j++];
    }

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Contributed on Sep 24 2023

Depressed Dugong

0 Answers Avg Quality 2/10

merge sort implementation

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#merge sort

#the merge algorithm
def merge(L1, L2, L):
  i = 0
  j = 0
  while i+j < len(L):
    if j == len(L2) or (i < len(L1) and L1[i] < L2[j]):
       L[i+j] = L1[i]
       i += 1
    else:
       L[i+j] = L2[j]
       j += 1

#main function
def merge_sort(L):

  n = len(L)
  if n < 2:
     return # list is already sorted

  # divide
  mid = n // 2 #midpoint
  L1 = L[0:mid] # the first half
  L2 = L[mid:n] # the second half
 
  # conquer with recursion
  merge_sort(L1) # sort first sub-list
  merge_sort(L2) # sort second sub-list

  # merge result
  merge(L1, L2, L) 

#example
L = [7, 5, 1, 4, 2, 8, 0, 9, 3, 6]
print('Before: ', L)
merge_sort(L)
print('After: ', L)

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Source: www.pynerds.com

Tags: implementation merge python

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Contributed on Apr 15 2024

John Maina

0 Answers Avg Quality 2/10

Implementation of the merge algorithm of merge sort

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Implementation of the merge algorithm of merge sort

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