238. Product of Array Except Self.py

# 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.)


# Bi way
class Solution:
    # @param {integer[]} nums
    # @return {integer[]}
    def productExceptSelf(self, nums):
        p = 1
        n = len(nums)
        output = []
        for i in range(0,n):
            output.append(p)
            p = p * nums[i]
        p = 1
        for i in range(n-1,-1,-1):
            output[i] = output[i] * p
            p = p * nums[i]
        return output


    def productexpectself(self, nums):
        p = 1
        n = len(nums)
        res = []
        for i in range(n):
            res.append(p)
            p *= nums[i]
        p=1
        for j in range(n-1,-1,-1):
            res[j] *= p
            p *= nums[j]
        return res