leetcode 238. Product of Array Except Self

Seawolf

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 mul = 1;
        int[] res = new int[nums.length];
        for(int i = 0; i<nums.length; i++){
            res[i] = 1;
        }
        for(int i = 0; i< nums.length; i++){
            res[i] = res[i] * mul;
            mul = mul * nums[i];
         }
        mul = 1;
        for(int i = nums.length -1 ; i>=0 ; i--){
            res[i] = res[i] * mul;
            mul = mul * nums[i];
        }
        
        return res;
    }
}