LeetCode 238. Product of Array Except Self

Given an array of n integers where n > 1, nums, return an array output such that output[i] is equal to the product of all the elements of nums except nums[i].

Solve it without division and in O(n).

For example, given [1,2,3,4], return [24,12,8,6].

Follow up:

Could you solve it with constant space complexity? (Note: The output array does not count as extra space for the purpose of space complexity analysis.)

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class Solution {
public:
vector<int> productExceptSelf(vector<int>& nums) {
vector<int> v(nums.size());
int right = 1;
v[0] = 1;
//左边所有数字的乘积
for(int i = 1; i < nums.size(); i++) {
v[i] = nums[i - 1] * v[i - 1];
}
for(int i = nums.size() - 2; i >= 0; i--) {
right = right * nums[i + 1];
v[i] = v[i] * right;
}
return v;
}
};