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：leetcode.com/problems/se…
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