MergeSort.c

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

void myMergeSort(int arr[], int size);
void printarr(int arr[], int length);
void mergeBothSide(int arr[], int leftarr[], int rightarr[], int halfLen, int rightHalfLen);

int main(void)
{
    int arr[] = {6, 5, 3, 1, 8, 7, 2, 4};
    int length = 8;
    printf("Original: ");
    printarr(arr, length);
    myMergeSort(arr, length);
    printf("END Merged: ");
    printarr(arr, length);
}

void mymergesort(int arr[], int size)
{
    if(size <= 1) return;
    
    int halfLen = ceil(size / 2);
    int leftarr[halfLen];
    int rightHalfLen = size - halfLen;
    int rightarr[rightHalfLen];
    myMergeSort(leftarr, halfLen);
    myMergeSort(rightarr, rightHalfLen);

    mergeBothSide(arr, leftarr, rightarr, halfLen, rightHalfLen);
}

void mergeBothSide(int arr[], int leftarr[], int rightarr[], int leftHalfLen, int rightHalfLen)
{
    int length = leftHalfLen + rightHalfLen;
    int leftIndex = 0, rightIndex = 0;
    for(int i = 0; i < length; i++)
    {
        if(rightIndex >= rightHalfLen) {
            arr[i] = leftarr[leftIndex];
            leftIndex++;
        } else if(leftIndex >= leftHalfLen) {
            arr[i] = rightarr[rightIndex];
            rightIndex++;
        } else if(leftarr[leftIndex] <= rightarr[rightIndex]) {
            arr[i] = leftarr[leftIndex];
            leftIndex++;
        } else {
            arr[i] = rightarr[rightIndex];
            rightIndex++;
        }
    }
}

void printarr(int arr[], int length) {
    printf("Print ARR: ");
    for(int i = 0; i < length; i ++)
    {
        printf("%d ", arr[i]);
    }
    printf("\n");
}