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Given two strings A and B of lowercase letters, return true if and only if we can swap two letters in A so that the result equals B. Example 1: Input: 阅读全文
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Given a binary tree, return the inorder traversal of its nodes' values. Example: Input: [1,null,2,3] 1 \ 2 / 3 Output: [1,3,2] Follow up: Recursive so 阅读全文
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The ability to debug and overall thinking need to improve Given a string, find the first non-repeating character in it and return it's index. If it do 阅读全文
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Given two strings s and t which consist of only lowercase letters. String t is generated by random shuffling string s and then add one more letter at 阅读全文
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Count the number of prime numbers less than a non-negative number, n. Example: Solution2: ssieving: need a helping array with false initialization: fa 阅读全文
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Given two strings s and t, determine if they are isomorphic. Two strings are isomorphic if the characters in s can be replaced to get t. All occurrenc 阅读全文
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All DNA is composed of a series of nucleotides abbreviated as A, C, G, and T, for example: "ACGAATTCCG". When studying DNA, it is sometimes useful to 阅读全文
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Given a group of two strings, you need to find the longest uncommon subsequence of this group of two strings. The longest uncommon subsequence is defi 阅读全文
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Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000. Example 1: Input: "babad" Output: 阅读全文
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Given a non-empty string check if it can be constructed by taking a substring of it and appending multiple copies of the substring together. You may a 阅读全文