No. 9 Palindrome Number （简单，PASS）

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No. 10 Regular Expression Matching (HARD)

https://leetcode.com/problems/regular-expression-matching/discuss/5723/My-DP-approach-in-Python-with-comments-and-unittest

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No. 11 Container With Most Water

注意点：本题目并不是求已给出的height中符合要求的sum最大，而是给出最大能盛水的量。

Solution: Two Pointers

Note: The most water = width * min(left, right), where width = j - i, i and j are the indexes of two sides.

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No. 12 Integer to Roman

将整数转换成罗马数字（Roman），字符表对应如下：

其中，有六种特殊情况，如下：

Solution：不断整除，分母分别为[1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1]。