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Given a string, your task is to count how many palindromic substrings in this string. The substrings with different start indexes or end indexes are c 阅读全文
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You are given a string representing an attendance record for a student. The record only contains the following three characters: 'A' : Absent. 'L' : L 阅读全文
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Given a string and an integer k, you need to reverse the first k characters for every 2k characters counting from the start of the string. If there ar 阅读全文
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Given a binary tree, you need to compute the length of the diameter of the tree. The diameter of a binary tree is the length of the longestpath betwee 阅读全文