Leetcode MySQL 178. Rank Scores

題目:

+----+-------+
| Id | Score |
+----+-------+
| 1  | 3.50  |
| 2  | 3.65  |
| 3  | 4.00  |
| 4  | 3.85  |
| 5  | 4.00  |
| 6  | 3.65  |
+----+-------+

LeetCode 5. Longest Palindromic Substring

題目:

超出字串中最長的字串。

Example 1:

Input: s = "babad"
Output: "bab"
Note: "aba" is also a valid answer.

Example 2:

Input: s = "cbbd"…

LeetCode 3. Longest Substring Without Repeating Characters

題目:

Input: s = "abcabcbb"
Output: 3
Explanation: The answer is "abc", with the length of 3.

找出字串中，不重複最長有多少。

LeetCode 20. Valid Parentheses

題目:

Example 1:

Input: s = "()"
Output: true

Example 2:

Input: s = "()[]{}"
Output: true

Example 3:

Input: s = "(]"…