【题目】

Given a non-negative integer represented asa non-empty array of digits, plus one to the integer.

 

You may assume the integer do not containany leading zero, except the number 0 itself.

 

The digits are stored such that the mostsignificant digit is at the head of the list.

 

　给定一个数组，将数加一，返回新的数组。比如[9,9]，返回[1,0,0]。

 

【思路】

 

数组末尾位加1，然后如果进位就向前一个数字加1.

【Python实现】

 

 classSolution(object):

   def plusOne(self, digits):

       """

       :type digits: List[int]

       :rtype: List[int]

       """

       digits_length = len(digits)

       if digits_length == 0:

           return [1]

       carry = 0#进位

       digits[digits_length - 1] += 1#末尾加1

       while digits_length > 0:

           digits[digits_length - 1] += carry

           if digits[digits_length - 1] >= 10:

               digits[digits_length - 1], carry= digits[digits_length - 1] % 10, digits[digits_length - 1] // 10

           else:

                carry = 0

                break

           digits_length -= 1

       if carry == 0:

           print(digits)

           return digits

       digits.insert(0,carry)#在digits[0]加入carry

       print(digits)

       return digits

                 

           

if __name__ == '__main__':

    S= Solution()

   digits = [1,2,1,9]

   S.plusOne(digits