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merge sort implementation

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John Maina answered on February 24, 2022 Popularity 2/10 Helpfulness 1/10

answer merge sort implementation

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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)

Popularity 2/10 Helpfulness 1/10 Language python

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

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merge sort function

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def merge_sort(arr):
    """Execute the merge sort algorithm"""
    if len(arr) > 1:
        # recursive case
        mid = len(arr) // 2 # find the midpoint of the array
        l = arr[:mid] # define the left half of the array
        r = arr[mid:] # define the right half of the array

        l = merge_sort(l) # sort the left half by calling this function
        r = merge_sort(r) # sort the right half by calling this function

        # now merge the two lists
        merged = [] # define an empty merged array
        while len(l) > 0 and len(r) > 0:
            # compare the heads of the left and right array
            if l[0] <= r[0]:
                # if the head of the left list is smaller than the head of the right list
                # pop the head of the left list and append it to the merged list
                merged.append(l.pop(0))
            else:
                # otherwise, pop the head of the right list and append that
                merged.append(r.pop(0))

        # add any elements remaining in the left or right list to the merged list
        merged = merged + l + r

        return merged
    else:
        # base case
        return arr

Popularity 10/10 Helpfulness 2/10 Language python

Source: Grepper

Tags: function functio

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Contributed on Feb 24 2022

Distinct Dragonfly

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]);
    }
  }
}

Popularity 10/10 Helpfulness 2/10 Language whatever

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++];
    }

Popularity 8/10 Helpfulness 1/10 Language cpp

Source: Grepper

Tags: algorithm algo

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Contributed on Sep 24 2023

Depressed Dugong

0 Answers Avg Quality 2/10

merge sort implementation

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