Given an absolute path for a file (Unix-style), simplify it. For example, {代码...}

There are a total of n courses you have to take, labeled from 0 to n - 1.Some courses may have prerequisites, for example to take course 0 you have to first take course 1, which is expressed as a pair: [0,1] Given the total number of courses and a list of prerequisite pairs, is it possible for yo...

Given a list of non negative integers, arrange them such that they form the largest number. For example, given [3, 30, 34, 5, 9], the largest formed number is 9534330. Note: The result may be very large, so you need to return a stringinstead of an integer.

A message containing letters from A-Z is being encoded to numbers using the following mapping: {代码...} Given an encoded message containing digits, determine the total number of ways to decode it. For example, Given encoded message "12", it could be decoded as "AB"(1 2) or "L" (12). The number o...

Given two strings s and t, write a function to determine if t is an anagram of s. For example, s = "anagram", t = "nagaram", return true. s = "rat", t = "car", return false. Note: You may assume the string contains only lowercase alphabets.

Given an unsorted array of integers, find the length of the longest consecutive elements sequence. For example, Given [100, 4, 200, 1, 3, 2], The longest consecutive elements sequence is [1, 2, 3, 4]. Return its length: 4. Your algorithm should run in O(n) complexity.

Given n, how many structurally unique BST's (binary search trees) that store values 1...n? For example, Given n = 3, there are a total of 5 unique BST's. {代码...}

Suppose a sorted array is rotated at some pivot unknown to you beforehand.(i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2). You are given a target value to search. If found in the array return its index, otherwise return -1. You may assume no duplicate exists in the array.

You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent houses have security system connected and it will automatically contact the police if two adjacent hou...

和Implement Queue using Stack类似，我们也可以用两个队列来模拟栈的操作。当push时，我们将数字offer进非空的队列就行了。当pop时，因为要拿的是队列最后一个数，我们先将它前面的数offer进另一个队列，然后单独拿出最后一个数，并且不再offer进另一个队列，这样，另一个队列就少了最后一个数，而我们也拿到了最后一个...

Compare two version numbers version1 and version2. If version1 > version2 return 1, if version1 < version2 return -1, otherwise return 0. You may assume that the version strings are non-empty and contain only digits and the . character. The . character does not represent a decimal point and...

Given a linked list, remove the nth node from the end of list andreturn its head.For example, Given linked list: 1->2->3->4->5, and n = 2. After removing the second node from the end, the linked listbecomes 1->2->3->5. Note: Given n will always be valid. Try to do thisin one ...

Given an integer n, return the number of trailing zeroes in n!. Note: Your solution should be in logarithmic time complexity.

Given numRows, generate the first numRows of Pascal's triangle. For example, given numRows = 5, Return {代码...}

Given an array and a value, remove all instances of that value in place and return the new length. The order of elements can be changed. It doesn't matter what you leave beyond the new length.

Given a string S, you are allowed to convert it to a palindrome by adding characters in front of it. Find and return the shortest palindrome you can find by performing this transformation. For example: Given "aacecaaa", return "aaacecaaa". Given "abcd", return "dcbabcd".

Given a non-empty binary search tree and a target value, find the value in the BST that is closest to the target. Note: Given target value is a floating point. You are guaranteed to have only one unique value in the BST that is closest to the target.

Given a string that contains only digits 0-9 and a target value, return all possibilities to add binary operators (not unary) +, -, or * between the digits so they evaluate to the target value. Examples: {代码...}

Implement a basic calculator to evaluate a simple expression string. The expression string may contain open ( and closing parentheses ), the plus + or minus sign -, non-negative integers and empty spaces . You may assume that the given expression is always valid. Some examples: {代码...} Note: Do...

There is a new alien language which uses the latin alphabet. However, the order among letters are unknown to you. You receive a list of words from the dictionary, where words are sorted lexicographically by the rules of this new language. Derive the order of letters in this language. For example,...

Given an Iterator class interface with methods: next() and hasNext(), design and implement a PeekingIterator that support the peek() operation -- it essentially peek() at the element that will be returned by the next call to next(). Here is an example. Assume that the iterator is initialized to t...

Given an array of citations (each citation is a non-negative integer) of a researcher, write a function to compute the researcher's h-index. According to the definition of h-index on Wikipedia: "A scientist has index h if h of his/her N papers have at least h citations each, and the other N − h p...

Given an array of n integers nums and a target, find the number of index triplets i, j, k with 0 <= i < j < k < n that satisfy the condition nums[i] + nums[j] + nums[k] < target. For example, given nums = [-2, 0, 1, 3], and target = 2. Return 2. Because there are two triplets which...

Implement an iterator over a binary search tree (BST). Your iterator will be initialized with the root node of a BST.Calling next() will return the next smallest number in the BST. Note: next() and hasNext() should run in average O(1) time and uses O(h) memory, where h is the height of the tree.

Given two integers representing the numerator and denominator of a fraction, return the fraction in string format.If the fractional part is repeating, enclose the repeating part in parentheses. For example, Given numerator = 1, denominator = 2, return "0.5". Given numerator = 2, denominator = 1, ...

The API: int read4(char *buf) reads 4 characters at a time from a file. The return value is the actual number of characters read. For example, it returns 3 if there is only 3 characters left in the file. By using the read4 API, implement the function int read(char *buf, int n) that reads n charac...

Given a non-negative number represented as an array of digits, plus one to the number. The digits are stored such that the most significant digit is at the head of the list.

Given a binary search tree and a node in it, find the in-order successor of that node in the BST. Note: If the given node has no in-order successor in the tree, return null.

Design an algorithm to encode a list of strings to a string. The encoded string is then sent over the network and is decoded back to the original list of strings. Machine 1 (sender) has the function:string encode(vector<string> strs) { // ... your code return encoded_string; } Machine 2 (re...

Implement an iterator to flatten a 2d vector. For example, Given 2d vector = {代码...} By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: [1,2,3,4,5,6].