面试题66. 构建乘积数组

题目：

 

 

解答：

 

 

class Solution {
public:
    vector<int> constructArr(vector<int>& a) 、
    {
        int n = a.size();
        vector<int> ret(n, 1);
        
        int left = 1;
        for (int i = 0; i < n; i ++) 
        {
            ret[i] = left;
            left = left * a[i];
        } 

        int right = 1;
        for (int i = n-1; i >= 0; i --) 
        {
            ret[i] *= right;
            right *= a[i];
        }
        return ret;
    }
};