题目描述 You are a product manager and currently leading a team to develop a new product. Unfortunately, the lates…

Find the Duplicate Number Given an array nums containing n + 1 integers where each integer is between 1 and n …

Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999. Su…

题目 给定一个二叉树，原地将它展开为链表。 例如，给定二叉树 1 / \ 2 5 / \ \ 3 4 6 将其展开为： 1 \ 2 \ 3 \ 4 \ 5 \ 6 解析 通过递归实现；可以用先序遍历，然后串成链表 主要思…

题目描述 Given an array S of n integers, find three integers in S such that the sum is closest to a given number, …

Constant Time Random Picker 设计一个数据结构，支持O(1)时间的查询，增加，删除，和得到其中随机元素的操作，可以认为其中的元素是数字。 哈希表数组 复杂度 时间 O(1) 空间 O(N) 思路…

1. 题目 There are two sorted arrays nums1 and nums2 of size m and n respectively. Find the median of the two sor…

  Given a string that contains only digits 0-9 and a target value, return all possibilities to …

  Given an integer n, return 1 – n in lexicographical order. For example, given 13, return: [1,10,1…

题目： Given a linked list, swap every two adjacent nodes and return its head. For example, Given 1->2-&g…

  Given a string, you need to reverse the order of characters in each word within a sentence while still …

  Given a string s, return all the palindromic permutations (without duplicates) of it. Return an em…