production_without_itself

class Solution:
    """
    @param: nums: Given an integers array A
    @return: A long long array B and B[i]= A[0] * ... * A[i-1] * A[i+1] * ... * A[n-1]
    """
    def productExcludeItself(self, nums):
        #  write your code here
        result = [1] * len(nums)
        for i in range(1,len(nums)):
            result[i] = result[i-1]*nums[i-1]
            # it means, for result [3], result[3] = result[2] * nums [2] = result[1] * nums[1] * nums[2]
            # = result[0] * nums[0] * nums[1] * nums[2] =nums[0] * nums[1] * nums[2]
            # last member needs nothing to change but
            # for result [2], result = result[1]*nums[1] = result[0]*nums[0]*nums[1]=nums[0]*nums[1]
            # lacking nums[3]

            # for result [1], result [1] = result [0] * nums[0]
            # lacking nums[2] and nums[3]

            #for result [0]
            #lacking nums[1] nums[2] and nums[3]
        cur = 1
        for i in range(len(nums)-1,0,-1):
            cur = cur * nums[i]
            result[i-1] = result[i-1]*cur
        return result