Product of Array Except Self, Java

Product of Array Except Self

//'main' method must be in a class 'Rextester'.
//Compiler version 1.8.0_111

import java.util.*;
import java.lang.*;
/*
Input:  [1,2,3,4]
Output: [24,12,8,6]
*/
class Rextester
{  
    public static void main(String args[])
    {
        System.out.println("Hello, World!");
        int[] ans = productExceptSelf_constantSpace(new int[]{3,5,2,4,3});
        for(int i:ans)
            System.out.print(i+" ");
    }

public static int[] productExceptSelf_constantSpace(int[] nums){
        //create ans array. Start with product of left elements
        int[] ans = new int[nums.length];
        ans[0]=1;
        for(int i=1;i<nums.length;i++){
            ans[i] = ans[i-1]*nums[i-1];
        }

//calculate product of right elements and store the answers in ans array directly
        int mul = 1;
        for(int j=nums.length-1;j>=0;j--){
            ans[j] = ans[j]*mul;
            mul *= nums[j]; 
        }
        return ans;
    }
    public static int[] productExceptSelf(int[] nums) {
        //create an array for product of all elements to the left
        int[] l = new int[nums.length];
        l[0] = 1;
        for(int i=1;i<nums.length;i++){
            l[i] = l[i-1]*nums[i-1];
        }

//create an array for product of all elements to the right
        int[] r = new int[nums.length];
        r[nums.length-1] = 1;
        for(int j = nums.length-2;j>=0;j--){
            r[j] = r[j+1]*nums[j+1];
        }

//create answer array
        int[] ans = new int[nums.length];
        for(int k=0;k<nums.length;k++){
            ans[k] = l[k]*r[k];
        }
        return ans;
    }
    
}


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