leetcode 1796. Second Largest Digit in a String（python）

描述

Given an alphanumeric string s, return the second largest numerical digit that appears in s, or -1 if it does not exist.

An alphanumeric string is a string consisting of lowercase English letters and digits.

Example 1:

Input: s = "dfa12321afd"
Output: 2
Explanation: The digits that appear in s are [1, 2, 3]. The second largest digit is 2.	

Example 2:

Input: s = "abc1111"
Output: -1
Explanation: The digits that appear in s are [1]. There is no second largest digit. 

Note:

1 <= s.length <= 500
s consists of only lowercase English letters and/or digits.

解析

根据题意，就是找出字符串中第二大的数字，没有则返回 -1 。如果是纯字母字符串直接返回 -1 ，否则先使用正则提取出所有的单个数字，然后去重之后判断剩余数字的个数，如果个数大于 1 则返回第二大数字，否则直接返回 -1 。

解答

class Solution(object):
    def secondHighest(self, s):
        """
        :type s: str
        :rtype: int
        """
        if s.isalpha():
            return -1
        r = [int(i) for i in re.findall('[0-9]{1}', s)]
        r = list(set(r))
        r.sort()
        if len(r) >= 2:
            return r[-2]
        return -1

运行结果

Runtime: 48 ms, faster than 19.05% of Python online submissions for Second Largest Digit in a String.
Memory Usage: 13.6 MB, less than 20.95% of Python online submissions for Second Largest Digit in a String.

原题链接：https://leetcode.com/problems/second-largest-digit-in-a-string/

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