ProductofArrayExceptSelf.java

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

// Solve it without division and in O(n).

// For example, given [1,2,3,4], return [24,12,8,6].

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

public class ProductOfArrayExceptSelf {
    public int[] productExceptSelf(int[] nums) {
        int n = nums.length;
        int[] result = new int[n];
        int left = 1;
        
        for(int i = 0; i < nums.length; i++) {
            if(i > 0) {
                left *= nums[i - 1];
            }
            
            result[i] = left;
        }
        
        int right = 1;
        
        for(int i = n - 1; i >= 0; i--) {
            if(i < n - 1) {
                right *= nums[i + 1];
            }
            
            result[i] *= right;
        }
        
        return result;
    }
}