mergeSort.c++

#include<iostream>
using namespace std;

void merge(int *arr, int s, int e){

    int mid = (s+e)/2;

    int len1 = mid - s +1;
    int len2 = e - mid;

    int *first = new int[len1];
    int *second = new int[len2];

    int mainArrayIndex = s;
    for (int i = 0; i < len1; i++)
    {
        first[i] = arr[mainArrayIndex++];
    }

    mainArrayIndex = mid+1;
    for (int i = 0; i < len2; i++)
    {
        second[i] = arr[mainArrayIndex++];
    }

    int index1 = 0;
    int index2 = 0;
    mainArrayIndex = s;
    
    while (len1 < index1 && len2 < index2)
    {
        if (first[index1] < second[index2])
        {
            arr[mainArrayIndex++] = first[index1++];
        } else {
            arr[mainArrayIndex++] = second[index2++];
        }
        
    }

    while(index1 < len1) {
        arr[mainArrayIndex++] = first[index1++];
    }

    while(index2 < len2 ) {
        arr[mainArrayIndex++] = second[index2++];
    }

    delete []first;
    delete []second;
    

}

void mergeSort(int *arr, int s, int e){
    if(s>=e){
        return ;
    }

    int mid = (s+e)/2;

    mergeSort(arr,s,mid);

    mergeSort(arr,mid+1,e);

    merge(arr,s,e);

}

int main(){

    return 0;
}