leetcode-238-Product of Array Except Self

Given an array nums of n integers where n > 1, return an array output such that output[i] is equal to the product of all the elements of nums except nums[i].

Example:

Input:  [1,2,3,4]
Output: [24,12,8,6]

Note: Please solve it without division and in O(n).

Follow up:
Could you solve it with constant space complexity? (The output array does not count as extra space for the purpose of space complexity analysis.)

class Solution {
    public int[] productExceptSelf(int[] nums) {
        int[] answer = new int[nums.length];
        int length = nums.length;
        
        answer[0] = 1;
        for(int i=1; i<length; i++)
        {
            answer[i] = nums[i-1] * answer[i-1];
        }
        
        int R=1;
        
        for(int i=length-1; i>=0; i--)
        {
            answer[i] = answer[i] * R;
            R *= nums[i];
        }
        
        return answer;
    }
}