Product of Array Except Self

 1 class Solution {
 2 public:
 3     vector<int> productExceptSelf(vector<int>& nums) {
 4         vector<int> output(nums.size(), 1);
 5         if(nums.empty())
 6                return output;
 7         int left=1, right=1;
 8         for(int i=0; i<nums.size(); i++)
 9         {
10             output[i] = left;
11             left = left * nums[i];
12         }
13         for(int i=nums.size()-1; i>=0; i--)
14         {
15             output[i] = right * output[i];
16             right = right * nums[i];            
17         }
18         
19         return output;
20     }
21 };