- Product of Array Except Self Medium
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Share 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] Constraint: It's guaranteed that the product of the elements of any prefix or suffix of the array (including the whole array) fits in a 32 bit integer.
Note: Please solve it without division and in O(n).
Follow up: Could you solve it with constant space complexity? (The output array does not count as extra space for the purpose of space complexity analysis.)
Accepted 543,421 Submissions 907,267
思路：头尾各遍历一遍,计算left[0...i]，right[i...0]的乘积 result数组的每一位为 result[i]=nums[0...i-1]*nums[i+1,len(nums)]
代码：python3
class Solution:
def productExceptSelf(self, nums: List[int]) -> List[int]:
res=[1]*len(nums)
left=1
right=1
for i in range(0,len(nums)-1):
left=left*nums[i]
res[i+1]=left
for j in range(len(nums)-1,0,-1):
right=right*nums[j]
res[j-1]=res[j-1]*right
print(res)
return res
时间复杂度：O(2m) 空间复杂度：O(m)
