西施豆腐渣

Feb 15 '12Given a linked list, swap every two adjacent nodes and return its head.For example,Given 1->2->3->4, you should return the list as 2->1->4->3.Your algorithm should use only

Combination Sum IIMar 7 '12Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.Each number in

Given a binary tree, find the maximum path sum.The path may start and end at any node in the tree.For example:Given the below binary tree, 1 / \ 2 3Return 6.key-point

Binary Tree Zigzag Level Order TraversalSep 29 '12Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the nex

Climbing StairsApr 3 '12You are climbing a stair case. It takes n steps to reach to the top.Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?

Given an unsorted integer array, find the first missing positive integer.For example,Given [1,2,0] return 3,and [3,4,-1,1] return 2.Your algorithm should run in O(n) time and uses constant s

Distinct SubsequencesOct 19 '12Given a string S and a string T, count the number of distinct subsequences of T in S.A subsequence of a string is a new string which is formed from the ori

Gray CodeMay 20 '12The gray code is a binary numeral system where two successive values differ in only one bit.Given a non-negative integer n representing the total number of bits in the c

Given a string s consists of upper/lower-case alphabets and empty space characters ' ', return the length of last word in the string.If the last word does not exist, return 0.Note: A word is

Jump GameMar 25 '12Given an array of non-negative integers, you are initially positioned at the first index of the array.Each element in the array represents your maximum jump length at

Jump Game IIMar 17 '12Given an array of non-negative integers, you are initially positioned at the first index of the array.Each element in the array represents your maximum jump length

Given a collection of intervals, merge all overlapping intervals.For example,Given [1,3],[2,6],[8,10],[15,18],return [1,6],[8,10],[15,18]./** * Definition for an interval. * st

Longest Valid ParenthesesMar 1 '12Given a string containing just the characters '(' and ')', find the length of the longest valid (well-formed) parentheses substring.For "(()", the lon

Palindrome NumberJan 4 '12Determine whether an integer is a palindrome. Do this without extra space.Some hints:Could negative integers be palindromes? (ie, -1)If you are thinki

Given two sorted integer arrays A and B, merge B into A as one sorted array.Note:You may assume that A has enough space to hold additional elements from B. The number of elements initialized in A

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists./** * Definition for singly-linked list. * struct

Multiply StringsMar 12 '12Given two numbers represented as strings, return multiplication of the numbers as a string.Note: The numbers can be arbitrarily large and are non-negative.

Sqrt(x)Apr 3 '12Implement int sqrt(int x).Compute and return the square root of x.class Solution {public: int sqrt(int x) { // Start typing your C/C++ solution b

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.For example,Given 1->2->3->3->4->4->5, return 1->2->5.Given 1->1->1

Follow up for "Remove Duplicates":What if duplicates are allowed at most twice?For example,Given sorted array A = [1,1,1,2,2,3],Your function should return length = 5, and A is now [1,1,2,2,3]

Valid PalindromeJan 13Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.For example,"A man, a plan, a canal: Panama" is a pal

Say you have an array for which the ith element is the price of a given stock on day i.Design an algorithm to find the maximum profit. You may complete at most two transactions.Note:You ma

Next PermutationImplement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers.If such arrangement is not possible, it must rearrange it as the lo

Validate if a given string is numeric.Some examples:"0" => true" 0.1 " => true"abc" => false"1 a" => false"2e10" => trueNote: It is intended for the problem statement to be a

inorder traversalclass Solution {public: vector inorderTraversal(TreeNode *root) { // Start typing your C/C++ solution below // DO NOT write int main() function vector

3SumJan 18 '12Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.Note:

Restore IP AddressesAug 8 '12Given a string containing only digits, restore it by returning all possible valid IP address combinations.For example:Given "25525511135",return ["255.25

Given am xn matrix, if an element is 0, set its entire row and column to 0. Do it in place.uncompletedclass Solution {public:    void setZeroes(vector > &matrix) {        // Start

Permutation SequenceMar 28 '12The set [1,2,3,…,n] contains a total of n! unique permutations.By listing and labeling all of the permutations in order,We get the following sequence (ie,

Word LadderFeb 11Given two words (start and end), and a dictionary, find the length of shortest transformation sequence from start to end, such that:Only one letter can be changed at

Minimum Window SubstringApr 15 '12Given a string S and a string T, find the minimum window in S which will contain all the characters in T in complexity O(n).For example,S = "ADOBECODE

Sum Root to Leaf Numbers2 daysGiven a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number.An example is the root-to-leaf path 1->2->3 which rep

Trapping Rain WaterMar 10 '12Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after raining.For e

N-QueensMar 20 '12The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other.Given an integer n, return all distinct sol

N-Queens IIMar 20 '12Follow up for N-Queens problem.Now, instead outputting board configurations, return the total number of distinct solutions. A good optimization example: when the req

Given a set of non-overlapping intervals, insert a new interval into the intervals (merge if necessary).You may assume that the intervals were initially sorted according to their start times.

Palindrome Partitioning IIMar 1Given a string s, partition s such that every substring of the partition is a palindrome.Return the minimum cuts needed for a palindrome partitioning o

String to Integer (atoi)Dec 27 '11Implement atoi to convert a string to an integer.Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask

Construct Binary Tree from Inorder and Postorder TraversalSep 30 '12Given inorder and postorder traversal of a tree, construct the binary tree.Note:You may assume that duplicates do not

Palindrome PartitioningFeb 28Given a string s, partition s such that every substring of the partition is a palindrome.Return all possible palindrome partitioning of s.For example, gi