(leetcode)Product of Array Except Self

 1 class Solution {
 2 public:
 3     vector<int> productExceptSelf(vector<int>& nums) {
 4         int len = nums.size();
 5         int start,end,sumlo,sumhi;
 6         vector<int> ans;
 7         for(int i = 0; i < len; ++i)
 8         {
 9             start = 0;
10             end = len -1;
11             sumlo = sumhi = 1;
12             while(start < i)
13             {
14                 sumlo *= nums[start++];
15             }
16             while(end > i)
17             {
18                 sumhi *= nums[end--];
19             }
20             ans.push_back(sumlo * sumhi);
21         }
22         
23         return ans;
24     }
25 };

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