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LeetCode第20题 Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. An input string is 阅读全文
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Write a function to find the longest common prefix string amongst an array of strings. If there is no common prefix, return an empty string "". Exampl 阅读全文
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LeetCode第13题 Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. For example, two is written as II in Roman numeral, ju 阅读全文
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LeetCode第9题 Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward. Example 1: Example 2: 阅读全文