class Solution {
public:
vector<int> multiply(const vector<int>& A) {
//先算i左半边,后算右半边,两边乘一下就好了
if(A.empty()) return vector<int>();
int n = A.size();
vector<int > B(n);
//左半边
for(int i = 0,p = 1;i < n;++i){
B[i] = p;
p *= A[i];
}
//右边
for(int i = n - 1,p = 1;~i;--i){
B[i] *= p;
p *= A[i];
}
return B;
}
};