ProductOfArrayExceptSelf.java

package array;

/**
 Created by gouthamvidyapradhan on 04/05/2017.

 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 static void main(String[] args)
    {
        int[] nums = {1,2,3,4};
        int[] result = new ProductOfArrayExceptSelf().productExceptSelf(nums);
        for (int r : result)
            System.out.print(r + " ");
    }

    public int[] productExceptSelf(int[] nums)
    {
        int[] result = new int[nums.length];
        for(int i = 0, temp = 1, l = nums.length; i < l; i++)
        {
            result[i] = temp;
            temp *= nums[i];
        }
        for(int i = nums.length - 1, temp = 1; i >= 0; i--)
        {
            result[i] = result[i] * temp;
            temp *= nums[i];
        }
        return result;
    }

}