hjhomw的博客

Description:Given 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 represents the number 123. Find the

Description:Implement wildcard pattern matching with support for ‘?’ and ‘*’. ‘?’ Matches any single character. ‘*’ Matches any sequence of characters (including the empty sequence). The matching sho

Description:Given an absolute path for a file (Unix-style), simplify it. For example, path = “/home/”, => “/home” path = “/a/./b/../../c/”, => “/c”Corner Cases: • Did you consider the case where pa

Description: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 w

Description:Given a string containing just the characters ’(’, ’)’, ’{’, ’}’, ’[’ and ’]’, determine if the input string is valid. The brackets must close in the correct order, ”()” and ”()[]” are al

Description: Given a string containing just the characters ’(’ and ’)’, find the length of the longest valid (wellformed) parentheses substring. For ”(()”, the longest valid parentheses substring is

Description：Given n non-negative integers representing the histogram’s bar height where the width of each bar is 1, find the area of largest rectangle in the histogram. 分析： 参考这两篇博文 http://blog.csdn

Description:Evaluate the value of an arithmetic expression in Reverse Polish Notation. Valid operators are +, -, *, /. Each operand may be an integer or another expression. Some examples: [“2”, “1”,

Description:Given a binary tree, return the postorder traversal of its nodes’ values. For example: Given binary tree {1,#,2,3}, return [3,2,1]. Note: Recursive solution is trivial, could you do it

Description:Write a function to find the longest common prefix string amongst an array of strings.分析： 先将第一个字符串与第二个字符串比较，找出公共部分，再与第三个字符串比较，依次类推。。。代码：#include <iostream>#include <vector>#include <stri

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

分析 细节题。注意几个测试用例： 1. 不规则输入，但是有效， ”-3924x8fc”， ” + 413”, 2. 无效格式， ” ++c”, ” ++1” 3. 溢出数据， ”2147483648”代码：#include <iostream>#include <sstream>#include <string.h>#include <limits.h>using namespace

Given two binary strings, return their sum (also a binary string). For example, 62 第 3 章 字符串 a = “11” b = “1” Return ”100”.代码：#include <iostream>#include <algorithm>using namespace std;string Add

Description:Given an array of strings, return all groups of strings that are anagrams. Note: All inputs will be in lower-case.分析： Anagram（回文构词法）是指打乱字母顺序从而得到新的单词，比如 “dormitory” 打乱字母顺 序会变成 “dirty room

Description: Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exist one unique longest palindromic substring.分析见：

Description:The count-and-say sequence is the sequence of integers beginning as follows: 1, 11, 21, 1211, 111221, … 1 is read off as “one 1” or 11. 11 is read off as “two 1s” or 21. 21 is read off

Description: Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999.分析：每次选择能表示的最大值，把对应的字符串连起来代码：#include <iostream>using namespace std; string Inte

Description:Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999.分析： 1~9: {“I”, “II”, “III”, “IV”, “V”, “VI”, “VII”, “VIII”, “IX”};10~90: {“X”, “

Description:Implement regular expression matching with support for ‘.’ and ‘*’. ‘.’ Matches any single character. ‘*’ Matches zero or more of the preceding element. The matching should cover the enti

Description:Given a binary tree, return the inorder traversal of its nodes’ values. For example: Given binary tree {1,#,2,3}, return [1,3,2]. Note: Recursive solution is trivial, could you do it i

Description:Given a binary tree, return the preorder traversal of its nodes’ values. For example: Given binary tree {1,#,2,3},return [1,2,3]. Note: Recursive solution is trivial, could you do it iter

Description: Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST.代码:#include <iostream>#include <vector>#include <stack>#define Elementype in

Description:Given an array where elements are sorted in ascending order, convert it to a height balanced BST.代码:#include <iostream>#include <vector>#include <stack>#define Elementype intusing namespa

Description:Given a binary tree, find its minimum depth. The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.代码:#include <iostream>#incl

Description:Given a binary tree, find its maximum depth. The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.分析： 同上题代码：#include <iostrea

Description:Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum. For example: Given the below binary tr

Desciption:Given a binary tree and a sum, find all root-to-leaf paths where each path’s sum equals the given sum. For example: Given the below binary tree and sum = 22, return代码：#include <iostream>#i

Description: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,Return 6.分析： 这题很难，路径可以从任意节点开始，到任意节点结束。可以利用“最大连

Description:Given a binary tree struct TreeLinkNode { int val; TreeLinkNode *left, *right, *next; TreeLinkNode(int x) : val(x), left(NULL), right(NULL), next(NULL) {} };Populate each next pointer

Description:Given a binary tree, determine if it is a valid binary search tree (BST). Assume a BST is defined as follows: • The left subtree of a node contains only nodes with keys less than the node

Description: Given n, generate all structurally unique BST’s (binary search trees) that store values 1…n. For example, Given n = 3, your program should return all 5 unique BST’s shown below. 代码：#inc

Description:Given a binary tree, return the bottom-up level order traversal of its nodes’ values. (ie, from left to right, level by level from leaf to root). For example: Given binary tree {3,9,20,#,

Description:Given a binary tree, return the level order traversal of its nodes’ values. (ie, from left to right, level by level). For example: Given binary tree {3,9,20,#,#,15,7}, return its level o

Description: Given a binary tree, return the zigzag level order traversal of its nodes’ values. (ie, from left to right, then right to left for the next level and alternate between). For example: Gi

Description:Given two binary trees, write a function to check if they are equal or not. Two binary trees are considered equal if they are structurally identical and the nodes have the same value.代码：#i

Description:Given preorder and inorder traversal of a tree, construct the binary tree. Note: You may assume that duplicates do not exist in the tree.分析： 先序遍历和中序遍历可以确定一颗二叉树。思想方法来自于网上#include <iostream

Description:Given inorder and postorder traversal of a tree, construct the binary tree. Note: You may assume that duplicates do not exist in the tree.分析：代码：#include <iostream>#include <vector>#inclu

Description:Given a binary tree, determine if it is height-balanced. For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node n

描述 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.分析： 这方法从网上找到的，简单清晰易懂。如果把上例的顺序改一下，就可以看出规律了。比如

Given 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 palindrome. ”race a car” is not a pa