构建积乘数组

 1 class Solution {
 2 public:
 3     vector<int> multiply(const vector<int>& A) {
 4         vector<int> B;
 5         if(A.size()<=1)return B;
 6         vector<int> arr1;
 7         vector<int> arr2;
 8         arr1.push_back(1);
 9         int sum=1;
10         for(int idx=0; idx<=A.size()-2; ++idx)
11         {
12             sum=sum*A[idx];
13             arr1.push_back(sum);
14         }
15         arr2.push_back(1);
16         sum=1;
17         for(int idx=A.size()-1; idx>=1; --idx)
18         {
19             sum=sum*A[idx];
20             arr2.push_back(sum);
21         }
22         int length=A.size();
23         for(int idx=0; idx<length; ++idx)
24         {
25             int tmp=arr1[idx]*arr2[length-1-idx];
26             B.push_back(tmp);
27         }
28         return B;
29     }
30 };