Grokking #200

class Solution {
  public int[] productExceptSelf(int[] nums) {

    int[] ans = new int[nums.length];
    Arrays.fill(ans, 1);

    // calculate shifted left prefix product
    for (int i = 1; i < nums.length; i++) {
      ans[i] = ans[i - 1] * nums[i - 1];
    }

    // calculate shifted right prefix product and answer
    int rightProduct = 1;
    for (int i = nums.length - 2; i >= 0; i--) {
      rightProduct = rightProduct * nums[i + 1];

      ans[i] = ans[i] * rightProduct;
    }

    return ans;
  }
}