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  • 238. Product of Array Except Self

    1. Question:

    238. Product of Array Except Self

    https://leetcode.com/problems/product-of-array-except-self/

    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).

    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.)

    2. Solution:

    class Solution:
        def productExceptSelf(self, nums):
            """
            :type nums: List[int]
            :rtype: List[int]
            """
            re = []
            if nums is None:
                return re
    
            size = len(nums)
            re = [1 for v in range(size)]
    
            for i in range(1, size):
                re[i] = re[i - 1] * nums[i - 1]
    
            right_product = 1
            for i in range(-1, -size - 1, -1):
                re[i] = re[i] * right_product
                right_product *= nums[i]
    
            return re

    3. Complexity Analysis

    Time Complexity : O(N)

    Space Complexity: O(1)

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  • 原文地址:https://www.cnblogs.com/ordili/p/9991987.html
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