题目描述 Sort a linked list in O(n log n) time using constant space complexity. 分析 O(n log n) 的时间复杂度，归并排序最好，因为它不会因…

题目描述 Given an absolute path for a file (Unix-style), simplify it. For example, path = “/home/”, => “/home” …

Reverse a linked list from position m to n. Do it in-place and in one-pass. For example: Given&…

Medium 这个面经题一做，暴露出来不少基础问题。比如hashmap的key是不能修改的，只能remove旧的再put新的，不可以modify. 还有hashMap的key, value一定要给自己多一点思路空间，就像…

翻转字符串里的单词 题目叙述 给定一个字符串，逐个翻转字符串中的每个单词。 示例： 输入: “the sky is blue”, 输出: “blue is sky the”…

  We are given head, the head node of a linked list containing unique integer values. We a…

  Given a string S, find the longest palindromic substring in S. You may assume that the maximum length o…

  Given an Iterator class interface with methods: next() and hasNext(), design and impleme…

  Given a non-empty string str and an integer k, rearrange the string such that the same characters are a…

  Design a data structure that supports all following operations in average O(1) time. &nb…

  Now you are given a string S, which represents a software license key which we would like to format. Th…

Palindrome Permutation Given a string, determine if a permutation of the string could form a palindrome. For e…