Given a string s and a non-empty string p, find all the start indices of p's anagrams in s.

push(x) -- Push element x to the back of queue.pop() -- Removes the element from in front of queue.peek() -- Get the front element.empty() -- Return whether the queue is empty.Example:

Given a binary tree, determine if it is a valid binary search tree (BST).

You are given several logs that each log contains a unique id and timestamp. Timestamp is a string that has the following format: Year:Month:Day:Hour:Minute:Second, for example, 2017:01:01:23:59:59. All domains are zero-padded decimal numbers.

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

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

A 2d grid map of m rows and n columns is initially filled with water. We may perform an addLand operation which turns the water at position (row, col) into a land. Given a list of positions to operate, count the number of islands after each addLand operation. An island is surrounded by water and ...

You are given a license key represented as a string S which consists only alphanumeric character and dashes. The string is separated into N+1 groups by N dashes.

Given an n-ary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level).

Given an n-ary tree, return the postorder traversal of its nodes' values.For example, given a 3-ary tree:Return its postorder traversal as: [5,6,3,2,4,1].Note: Recursive solution is trivial, could you do it iteratively?

Given an n-ary tree, return the preorder traversal of its nodes' values.For example, given a 3-ary tree:Return its preorder traversal as: [1,3,5,6,2,4].Note: Recursive solution is trivial, could you do it iteratively?

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

Given a singly linked list L: L0→L1→…→Ln-1→Ln,reorder it to: L0→Ln→L1→Ln-1→L2→Ln-2→…

Sort a linked list in O(n log n) time using constant space complexity.

Given an arbitrary ransom note string and another string containing letters from all the magazines, write a function that will return true if the ransom note can be constructed from the magazines ; otherwise, it will return false.

According to the Wikipedia's article: "The Game of Life, also known simply as Life, is a cellular automaton devised by the British mathematician John Horton Conway in 1970."

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

Given two non-negative integers num1 and num2 represented as string, return the sum of num1 and num2.

A sentence S is given, composed of words separated by spaces. Each word consists of lowercase and uppercase letters only.

Given an array of meeting time intervals consisting of start and end times [[s1,e1],[s2,e2],...] (si < ei), find the minimum number of conference rooms required.

Given a binary tree, you need to compute the length of the diameter of the tree. The diameter of a binary tree is the length of the longest path between any two nodes in a tree. This path may or may not pass through the root.

A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down).

An array is monotonic if it is either monotone increasing or monotone decreasing.

Given a string, sort it in decreasing order based on the frequency of characters.

Given an array consists of non-negative integers, your task is to count the number of triplets chosen from the array that can make triangles if we take them as side lengths of a triangle.Example 1:Input: [2,2,3,4]Output: 3Explanation:Valid combinations are: 2,3,4 (using the first 2)2,3,4 (using t...

Each of the digits 1-9 must occur exactly once in each row.Each of the digits 1-9 must occur exactly once in each column.Each of the the digits 1-9 must occur exactly once in each of the 9 3x3 sub-boxes of the grid.Empty cells are indicated by the character '.'.

Given a string containing just the characters '(' and ')', find the length of the longest valid (well-formed) parentheses substring.

You have a total of n coins that you want to form in a staircase shape, where every k-th row must have exactly k coins.

We define the Perfect Number is a positive integer that is equal to the sum of all its positive divisors except itself.

Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitted across a network connection link to be reconstructed later in the same or another computer environment.