le119126的专栏

A message containing letters from A-Z is being encoded to numbers using the following mapping:'A' -> 1'B' -> 2...'Z' -> 26Given an encoded message containing digits, determine the total numb

Given a binary tree, find the maximum path sum.For this problem, a path is defined as any sequence of nodes from some starting node to any node in the tree along the parent-child connections. The

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. 1 3 3 2 1 \

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 tota

Given an unsorted array of integers, find the length of the longest consecutive elements sequence.For example,Given [100, 4, 200, 1, 3, 2],The longest consecutive elements sequence is [1, 2, 3

别人讲得很详细，题目有点难，就转 了：http://www.cnblogs.com/ShaneZhang/p/3748494.htmlGiven two words (beginWord and endWord), and a dictionary's word list, find all shortest transformation sequence(s) from beginW

Given a 2D board containing 'X' and 'O', capture all regions surrounded by 'X'.A region is captured by flipping all 'O's into 'X's in that surrounded region.For example,X X X XX O O X

Given a string s and a dictionary of words dict, determine if s can be segmented into a space-separated sequence of one or more dictionary words.For example, givens = "leetcode",dict = ["leet"

Given a singly linked list L: L0→L1→…→Ln-1→Ln,reorder it to: L0→Ln→L1→Ln-1→L2→Ln-2→…You must do this in-place without altering the nodes' values.For example,Given {1,2,3,4}, reorder it t

Given a string s and a dictionary of words dict, add spaces in s to construct a sentence where each word is a valid dictionary word.Return all such possible sentences.For example, givens = "

Given a string s, partition s such that every substring of the partition is a palindrome.Return all possible palindrome partitioning of s.For example, given s = "aab",Return [ ["aa","

http://zh-cn.enc.tfode.com/%E7%BA%A6%E7%91%9F%E5%A4%AB%E6%96%AF%E9%97%AE%E9%A2%98http://blog.youkuaiyun.com/niuox/article/details/9269731约瑟夫斯问题（有时也称为约瑟夫斯置换），是一个出现在计算机科学和数学中的问题。在计算机编程的算法中，类似问题又称为

Given a triangle, find the minimum path sum from top to bottom. Each step you may move to adjacent numbers on the row below.For example, given the following triangle[ [2], [3,4],

KMP算法是一种改进的字符串匹配算法思路：http://www.cnblogs.com/c-cloud/p/3224788.html对于next的理解：next[i] 表示i点不匹配（不包括i点）时，前面有next[i]个匹配的前缀（0，next[i]）下次要跳转到next[i]开始比较，P[K]不等于P[q]时（图中是j），由于已经到了目前的k，q了，那么 p[0]……p[k-1] 与 ...

转自：http://blog.youkuaiyun.com/worldwindjp/article/details/21694179Two elements of a binary search tree (BST) are swapped by mistake.Recover the tree without changing its structure.Note:A solution us

转自：http://blog.youkuaiyun.com/ljiabin/article/details/41699241点击打开链接【题目】Given a binary tree, determine if it is a valid binary search tree (BST).Assume a BST is defined as follows:The le

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", ret

Given preorder and inorder traversal of a tree, construct the binary tree.Note:You may assume that duplicates do not exist in the tree./** * Definition for a binary tree node. * struct Tre

参考 http://blog.youkuaiyun.com/zhongkeli/article/details/8847694  ---没有加 strA[lenA-1]==strB[lenB-1]，有误如最后一个7行6列是 4，6行5列是3 ，但是strA[7]是B ，strB[6]是A 所以不对，要加strA[lenA-1]==strB[lenB-1]

Distinct SubsequencesGiven 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 original string by

Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; }Populate each next pointer to point to its next right node.

Given an index k, return the kth row of the Pascal's triangle.For example, given k = 3, [1], [1,1], [1,2,1], [1,3,3,1], [1,4,6,4,1]Return [1,3,3,1].Note:Could you

Best Time to Buy and Sell Stock I Say you have an array for which the ith element is the price of a given stock on day i.If you were only permitted to complete at most one transaction (ie, buy

Given a string s, partition s such that every substring of the partition is a palindrome.Return the minimum cuts needed for a palindrome partitioning of s.For example, given s = "aab",Return

Design and implement a data structure for Least Recently Used (LRU) cache. It should support the following operations: get and set.get(key) - Get the value (will always be positive) of the key if

Given an input string, reverse the string word by word.For example,Given s = "the sky is blue",return "blue is sky the".思路：预处理，删除首尾空格。先翻转每一个单词，再全部翻转。在翻转每一个单词时，删除多余空格注意：1.删除连续空格，判断下个位置时一定

题目Given an array of integers, return indices of the two numbers such that they add up to a specific target.You may assume that each input would have exactly one solution.Example:Given

Find the contiguous subarray within an array (containing at least one number) which has the largest product.For example, given the array [2,3,-2,4],the contiguous subarray [2,3] has the largest

Follow up for "Find Minimum in Rotated Sorted Array":What if duplicates are allowed?Would this affect the run-time complexity? How and why?Suppose a sorted array is rotated at some pivot u

You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a link

转自：http://blog.youkuaiyun.com/yutianzuijin/article/details/11499917/这是我做的第二个leetcode题目，一开始以为和第一个一样很简单，但是做的过程中才发现这个题目非常难，给人一种“刚上战场就踩上地雷挂掉了”的感觉。后来搜了一下leetcode的难度分布表（leetcode难度及面试频率）才发现，该问题是难度为5的问题，真是小看了

转自：http://www.cnblogs.com/TenosDoIt/p/3675788.html?utm_source=tuicoolLeetCode:Longest Palindromic Substring 最长回文子串题目链接Given a string S, find the longest palindromic substring in S. You

转自：http://www.cnblogs.com/sanghai/p/3632528.html题目：The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a

Implement 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 yourself what are the possible input ca

/** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */clas

Given n points on a 2D plane, find the maximum number of points that lie on the same straight line.法一：两点确定一条直线（两两组合），然后在判断其他点是否在这条直线上，O（n^3）法二：遍历每一个点i {其他点j与该点i组成直线的斜率xl，斜率相同，统计加1----斜率相同又过同一个点i

Sort a linked list in O(n log n) time using constant space complexity./** * Definition for singly-linked list. * public class ListNode { * int val; * ListNode next; * ListNode(int

Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors.OJ's undirected graph serialization:Nodes are labeled uniquely.We use # as a separator for each

There are N gas stations along a circular route, where the amount of gas at station i is gas[i].You have a car with an unlimited gas tank and it costs cost[i] of gas to travel from station i to

There are N children standing in a line. Each child is assigned a rating value.You are giving candies to these children subjected to the following requirements:Each child must have at least on