LeetCode-238. Product of Array Except Self [C++][Java]

LeetCode-238. Product of Array Except Selfhttps://leetcode.com/problems/product-of-array-except-self/

Given an integer array nums, return an array answer such that answer[i] is equal to the product of all the elements of nums except nums[i].

The product of any prefix or suffix of nums is guaranteed to fit in a 32-bit integer.

You must write an algorithm that runs in O(n) time and without using the division operation.

Example 1:

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

Example 2:

Input: nums = [-1,1,0,-3,3]
Output: [0,0,9,0,0]

Constraints:

2 <= nums.length <= 10^5-30 <= nums[i] <= 30The product of any prefix or suffix of nums is guaranteed to fit in a 32-bit integer.

Follow up: Can you solve the problem in O(1) extra space complexity? (The output array does not count as extra space for space complexity analysis.)

class Solution {
public:
    vector productExceptSelf(vector& nums) {
        int n = nums.size(), left = 1, right = 1;
        vector products(n, 1);
        for (int i=1; i=0; i--) {
            right *= nums[i + 1];
            products[i] *= right;
        }
        return products;
    }
};

class Solution {
    public int[] productExceptSelf(int[] nums) {
        int n = nums.length, left = 1, right = 1;
        int[] products = new int[n];
        Arrays.fill(products, 1);
        for (int i=1; i=0; i--) {
            right *= nums[i + 1];
            products[i] *= right;
        }
        return products;
    }
}