Another corner case is the path might contain multiple slashes '/' together, such as "/home//foo/".

Evaluate the value of an arithmetic expression in Reverse Polish Notation.

Given a set of n nuts of different sizes and n bolts of different sizes. There is a one-one mapping between nuts and bolts. Comparison of a nut to another nut or a bolt to another bolt is not allowed. It means nut can only be compared with bolt and bolt can only be compared with nut to see which ...

Given a 2D binary matrix filled with 0's and 1's, find the largest square containing all 1's and return its area.

Given n points on a 2D plane, find the maximum number of points that lie on the same straight line.

The structure of Segment Tree is a binary tree which each node has two attributes start and end denote an segment / interval.

Permutations I Problem Given a list of numbers, return all possible permutations. Example For nums = [1,2,3], the permutations are: [ [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], [3,2,1]] Challenge Do it without recursion. Solution Recursion {代码...} Permutations II Problem Given a collection of...

For a given sorted array (ascending order) and a target number, find the first index of this number in O(log n) time complexity.

For a given source string and a target string, you should output the first index(from 0) of target string in source string.

Implement a stack with min() function, which will return the smallest number in the stack.

Given two values k1 and k2 (where k1 < k2) and a root pointer to a Binary Search Tree. Find all the keys of tree in range k1 to k2. i.e. print all x such that k1<=x<=k2 and x is a key of given BST. Return all the keys in ascending order.

when number is divided by 3, print "fizz".when number is divided by 5, print "buzz".when number is divided by both 3 and 5, print "fizz buzz".

Given a string and an offset, rotate string by offset. (rotate from left to right)

Design an algorithm and write code to serialize and deserialize a binary tree. Writing the tree to a file is called 'serialization' and reading back from the file to reconstruct the exact same binary tree is 'deserialization'.

Merge two given sorted integer array A and B into a new sorted integer array.

In array [9,3,2,4,8], the 3rd largest element is 4.In array [1,2,3,4,5], the 1st largest element is 5, 2nd largest element is 4, 3rd largest element is 3 and etc.

Ugly number is a number that only have factors 3, 5 and 7.Design an algorithm to find the Kth ugly number. The first 5 ugly numbers are 3, 5, 7, 9, 15 ...

if n=12, k=1 in [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12], we have FIVE 1's (1, 10, 11, 12)

Write an algorithm which computes the number of trailing zeros in n factorial.

Write a function that add two numbers A and B. You should not use + or any arithmetic operators.

Given a string containing only digits, restore it by returning all possible valid IP address combinations.

Cosine similarity is a measure of similarity between two vectors of an inner product space that measures the cosine of the angle between them. The cosine of 0° is 1, and it is less than 1 for any other angle.See wiki: Cosine SimilarityHere is the formula:Given two vectors A and B with the same si...

Given a linked list, reverse the nodes of a linked list k at a time and return its modified list.

Given a digit string, return all possible letter combinations that the number could represent.A mapping of digit to letters (just like on the telephone buttons) is given below.

Flatten a binary tree to a fake "linked list" in pre-order traversal.Here we use the right pointer in TreeNode as the next pointer in ListNode.

Problem Implement a function to check if a linked list is a palindrome. Example Given 1->2->1, return true. Key create new list nodes: {代码...} Solution {代码...}

Given a linked list, swap every two adjacent nodes and return its head.

Remove all elements from a linked list of integers that have value val.

Given a string s, partition s such that every substring of the partition is a palindrome.

Design a data structure that supports the following two operations: addWord(word) and search(word)