题目：​​原题链接​​（简单）

标签：字符串

解法一：

class Solution:
    def secondHighest(self, s: str) -> int:
        biggest = 10
        for i in range(9, -1, -1):
            if str(i) in s:
                if biggest == 10:  # 没有找到过数字
                    biggest = i
                elif i != biggest:
                    return i
        return -1