lc66. Plus OneGiven a non-empty array of digits representing

Plus One Easy

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

The digits are stored such that the most significant digit is at the head of the list, and each element in the array contain a single digit.

You may assume the integer does not contain any leading zero, except the number 0 itself.

Example 1:

Input: [1,2,3] Output: [1,2,4] Explanation: The array represents the integer 123. Example 2:

Input: [4,3,2,1] Output: [4,3,2,2] Explanation: The array represents the integer 4321.

思路：从尾部遍历，数字为9，有进位，flag值为True，继续遍历，不为9，值加一，返回数组，遍历完，flag为True，在数组头部insert（0，1）

代码：python3

class Solution:
    def plusOne(self, digits):
        flag = False
        for index,value in enumerate(list(reversed(digits))):
            if value==9:
                flag = True
                digits[len(digits)-index-1]=0
                print(index)
                print(digits[index])
            else:
                digits[len(digits)-index-1]=value+1
                return digits
        if flag == True:
            digits.insert(0,1)
            return digits
if __name__=='__main__':
    print(Solution().plusOne([1,2,3]));