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LeetCode - Longest Palindromic Substring

Question Definition

Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000.

LeetCode - Kth Smallest Element in a Sorted Matrix

Question Definition

Given a n x n matrix where each of the rows and columns are sorted in ascending order, find the kth smallest element in the matrix.

LeetCode - Kth Smallest Element in a BST

Question Definition

Given a binary search tree, write a function kthSmallest to find the kth smallest element in it.

LeetCode - Compare Version Numbers

Question Definition

Compare two version numbers version1 and version2. If version1 > version2 return 1, if version1 < version2 return -1, otherwise return 0.

LeetCode - Valid Parenthesis String

Question Definition

Given a string containing only three types of characters: ‘(‘, ‘)’ and ‘*’, write a function to check whether this string is valid. We define the validity of a string by these rules:

1. Any left parenthesis ‘(‘ must have a corresponding right parenthesis ‘)’.
2. Any right parenthesis ‘)’ must have a corresponding left parenthesis ‘(‘.
3. Left parenthesis ‘(‘ must go before the corresponding right parenthesis ‘)’.
4. ‘*’ could be treated as a single right parenthesis ‘)’ or a single left parenthesis ‘(‘ or an empty string.
5. An empty string is also valid.