Insertion Sort implementation in C++

insertionsort.cpp

#include <iostream>
using namespace std;
#define MAX 10

void insertionSort(int arr[]) {
  int key, j;
  for (int i = 1; i < MAX; i++) {
    key = arr[i];
    j = i - 1;

    while (j >= 0 && arr[j] > key) {
      arr[j + 1] = arr[j];
      j = j - 1;
    }

    arr[j + 1] = key;
  }
}

int main() {
  int arr[MAX] = {10, 9, 8, 7, 6, 5, 4, 3, 2, 1};
  insertionSort(arr);
  for (int i = 0; i < MAX; i++) {
    cout << arr[i] << " ";
  }

  cout << endl;
  return 0;
}