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Simplify Path Given an absolute path for a file (Unix-style), simplify it. For example, path = "/home/", => "/home" path = "/a/./b/../../c/", => "/c" click to show corner cases. Corn

You need to construct a binary tree from a string consisting of parenthesis and integers.The whole input represents a binary tree. It contains an integer followed by zero, one or two pairs of parenthes

Given s1, s2, s3, find whether s3 is formed by the interleaving of s1 and s2.For example, Given: s1 = “aabcc”, s2 = “dbbca”,When s3 = “aadbbcbcac”, return true. When s3 = “aadbbbaccc”, return false

434. Number of Segments in a String Count the number of segments in a string, where a segment is defined to be a contiguous sequence of non-space characters. For example, Input: "Hello, my

468. Validate IP Address In this problem, your job to write a function to check whether a input string is a valid IPv4 address or IPv6 address or neither. IPv4 addresses are canonically represente

331. Verify Preorder Serialization of a Binary Tree One way to serialize a binary tree is to use pre-order traversal. When we encounter a non-null node, we record the node's value. If it is a nul

451. Sort Characters By Frequency Given a string, sort it in decreasing order based on the frequency of characters. Example 1: Input: "tree" Output: "eert" Explanation: 'e' appears twice wh

459. Repeated Substring Patternk To on Given a non-empty string check if it can be constructed by taking a substring of it and appending multiple copies of the substring together. You may assume

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,

151. Reverse Words in a String Given an input string, reverse the string word by word. For example, Given s = "the sky is blue", return "blue is sky the". Update (2015-02-12): For C prog

Given a sequence of words, check whether it forms a valid word square. A sequence of words forms a valid word square if the kth row and column read the exact same string, where 0 ≤ k  Note: T

Given a non-empty string containing an out-of-order English representation of digits 0-9, output the digits in ascending order. Note: Input contains only lowercase English letters.Input is g

Given a string that consists of only uppercase English letters, you can replace any letter in the string with another letter at most k times. Find the length of a longest substring containing all repe

395. Longest Substring with At Least K Repeating Characters Find the length of the longest substring T of a given string (consists of lowercase letters only) such that every character in T appear

438. Find All Anagrams in a String Given a string s and a non-empty string p, find all the start indices of p's anagrams in s. Strings consists of lowercase English letters only and th

388. Longest Absolute File Path Suppose we abstract our file system by a string in the following manner: The string "dir\n\tsubdir1\n\tsubdir2\n\t\tfile.ext" represents: dir subdir1 s

Question Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring.

Given a 01 matrix M, find the longest line of consecutive one in the matrix. The line could be horizontal, vertical, diagonal or anti-diagonal.Example: Input: [[0,1,1,0], [0,1,1,0], [0,0,0,1]] O