# 238. Product of Array Except Self

## 刷题内容

• https://leetcode.com/problems/two-sum

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

Example:

Input:  [1,2,3,4]
Output: [24,12,8,6]
Note: Please solve it without division and in O(n).

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


## 解题方案

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

beats 100.00%

class Solution {
public int[] productExceptSelf(int[] nums) {
int[] res = new int[nums.length];

for (int i = 0; i < nums.length; i++) {
res[i] = 1;
}

int left = 1;
for (int i = 0; i < nums.length - 1; i++) {
left *= nums[i];
res[i+1] *= left;
}

int right = 1;
for (int i = nums.length - 1; i > 0; i--) {
right *= nums[i];
res[i-1] *= right;
}

return res;
}
}