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Given two integers representing the numerator and denominator of a fraction, return the fraction in string format. If the fractional part is repeating 阅读全文
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You are playing the following Bulls and Cows game with your friend: You write down a number and ask your friend to guess what the number is. Each time 阅读全文
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You are given a map in form of a two-dimensional integer grid where 1 represents land and 0 represents water. Grid cells are connected horizontally/ve 阅读全文
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Given a pattern and a string str, find if str follows the same pattern. Here follow means a full match, such that there is a bijection between a lette 阅读全文
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Given a pattern and a string str, find if str follows the same pattern. Here follow means a full match, such that there is a bijection between a lette 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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Given a string s, find the longest palindromic subsequence's length in s. You may assume that the maximum length of s is 1000. Example 1:Input: Output 阅读全文
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递归的基本概念:程序调用自身的编程技巧称为递归,是函数自己调用自己. 一个函数在其定义中直接或间接调用自身的一种方法,它通常把一个大型的复杂的问题转化为一个与原问题相似的规模较小的问题来解决,可以极大的减少代码量.递归的能力在于用有限的语句来定义对象的无限集合. 使用递归要注意的有两点: 1)递归就 阅读全文
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Given a list of unique words, find all pairs of distinct indices (i, j) in the given list, so that the concatenation of the two words, i.e. words[i] + 阅读全文