Merge Sort

#include <iostream>

using namespace std;

void mergeSort(int arr[], int size);
void mergeSort(int arr[], int leftIndex, int rightIndex);
void mergeSortMerge(int arr[], int l, int m, int r);

int main(){
    int arr[10] = {15, 6, 8, -1, 0, 23, 1, 42, 32, 44};

    mergeSort(arr, 10);

    for(auto i : arr)
        cout << i << " ";
}

void mergeSort(int arr[], int size){
    mergeSort(arr, 0, size - 1);
}

void mergeSort(int arr[], int leftIndex, int rightIndex){
    if(leftIndex < rightIndex){
        int middle = (leftIndex + rightIndex) / 2;

        mergeSort(arr, leftIndex, middle);
        mergeSort(arr, middle + 1, rightIndex);
        mergeSortMerge(arr, leftIndex, middle, rightIndex);
    }
}

void mergeSortMerge(int arr[], int l, int m, int r){
    //arr1: l to m
    //arr2: m + 1 to r
    int* arr1 = new int[m - l + 1],
        *arr2 = new int[r - m];


    for(int i = 0; i < m - l + 1; i++){
        arr1[i] = arr[i + l];
        arr2[i] = arr[i + m + 1];
    }

    int f = 0, s = 0, i = l;

    while(f < m - l + 1 && s < r - m){
        arr[i++] = arr1[f] < arr2[s] ? arr1[f++] : arr2[s++];
    }

    while(f < m - l + 1){
        arr[i++] = arr1[f++];
    }

    while(s < r - m){
        arr[i++] = arr2[s++];
    }

    delete[] arr1;
    delete[] arr2;
}