class Solution {
public:
vector<int> productExceptSelf(vector<int>& nums) {
if(nums.empty()) return {};
int len = nums.size();
vector<int> res(len, 1);
for(int i=1;i<nums.size();i++){
res[i] = res[i-1]*nums[i-1];
}
int right = 1;
for(int i=nums.size()-2;i>=0;i--){
res[i] *= right*nums[i+1];
right *= nums[i+1];
}
return res;
}
};