Merge_sort

#include <bits/stdc++.h>
using namespace std;
const int N = 1e5;
int arr[N];
void merge(int *arr , int l , int mid , int r){
		int i = 0 , j = l , k = l;
		int L[mid - l + 1] , R[r - mid]  ;
		for( i = l ; i <= mid ; i++){
				L[i - l] = arr[i];
		}

		/*  ERROR
		for ( i = mid+1; i < r; i++) {
				R[i - (mid + 1)] = arr[i];
		}
		*/

		// CORRECTED
		for ( i = mid+1; i <= r; i++) {
				R[i - (mid + 1)] = arr[i];
		}

		int left = mid -l +1 , right = r - mid;
		i = 0 , j = 0 , k = l;
		while(i < left && j < right ){
			if(L[i] <= R[j]){
					arr[k++] = L[i];
					i++;
			}
			else{
				arr[k++] = R[j];
				j++;
			}
		}
		while(i < left)arr[k++] = L[i] , i++;
		while(j < right)arr[k++] = R[j] ,j++;

}

void merge_sort(int *arr , int l , int r){
	if(l >= r)return;
		int mid = (l + r) >> 1;
		merge_sort(arr , l , mid);
		merge_sort(arr , mid+1 ,r);
		merge(arr , l , mid , r);
}

int main(int argc, char const *argv[])
{
	int n;
   cin >> n;
	for (size_t i = 0; i < n; i++) {
		cin >> arr[i];
	}
	merge_sort(arr , 0 , n-1);
	for (size_t i = 0; i < n; i++) {
	cout << arr[i] << ' ';
	}
	return 0;
}