巧妙解法：构建乘积数组

class Solution {
public:
    vector<int> multiply(const vector<int>& A) {
        
        int n = A.size();
        
        vector<int> B;
        if(n == 0)return B;
        
        B[0] = 1;
        
        
        for(int i = 1; i < n; i++){
            B[i] = B[i-1] * A[i-1];
        }
        int temp = 1;
        for(int j = n-2; j >= 0; j-- ){
            temp *= A[j+1];
            B[j] *= temp;
        }
        return B;
    }
};