Products of all numbers in the array

This is google coding interview question:

Given an array of numbers, replace each number with the

product of all the numbers in the array except the number itself *without* using division

https://www.glassdoor.com/Interview/Given-an-array-of-numbers-replace-each-number-with-the-product-of-all-the-numbers-in-the-array-except-the-number-itself-w-QTN_9132.htm

The key to this solution is construct the accessory arrays which assists the solution. Here are the code 


Recursive way

	public static int[] products(int[] nums){
	int[] products = new int[nums.length];
	productRec(nums, products, 0);
	return products;
	}
	public static int productRec(int[] nums, int[] products, int i){
	if(i==nums.length-1)
	return 1;
	products[i] = (i==0?1:products[i-1] * nums[i-1]);
	int p = productRec(nums, products, i+1) * nums[i+1];
	products[i] = products[i] * p;
	return p;
	}

view raw productRec.java hosted with ❤ by GitHub

Iterative way:

	public static int[] product(int[] nums){
	int len = nums.length;
	int[] result = new int[len];
	result[0] = 1;
	for(int i=1; i<len; i++){
	result[i] = result[i-1] * nums[i-1];
	}
	int p = 1;
	for(int i=len-2; i>=0; i--){
	p = p * nums[i+1];
	result[i] = result[i] * p;
	}
	return result;
	}

view raw productIterative.java hosted with ❤ by GitHub