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原创 LeetCode总结

LeetCode目前做了有132题了，是时候边复习边总结了。题目Blog类型难度

2013-10-08 21:56:01 2379

原创 LeetCode——Palindrome Partitioning II

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",Retu

2013-09-27 02:44:11 1255

原创 LeetCode——Palindrome Partition

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"

2013-09-27 01:35:32 880

原创 LeetCode——Surrounded Regions

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

2013-09-27 00:58:52 1721

原创 LeetCode——Longest Consecutive Sequence

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,

2013-09-26 21:38:49 576

原创 LeetCode——Word Ladder II

Given two words (start and end), and a dictionary, find all shortest transformation sequence(s) from start to end, such that:Only one letter can be changed at a timeEach intermediate word

2013-09-26 20:43:32 2015

原创 LeetCode——Sum Root to Leaf Numbers

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 to

2013-09-26 18:52:28 779

原创 LeetCode——Word Ladder

Given 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 a timeEach intermediat

2013-09-26 18:46:30 573

原创 LeetCode——Valid Palindrome

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 no

2013-09-26 12:58:33 1138

原创 LeetCode——Binary Tree Maximum Path Sum

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.»

2013-09-26 12:49:30 754

原创 LeetCode——Best Time to Buy and Sell Stock III

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

2013-09-26 01:51:23 4882

原创 LeetCode——Best Time to Buy and Sell Stock II

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 as many transactions as you like (ie, buy

2013-09-26 00:56:31 975

原创 LeetCode——Best Time to Buy and Sell Stock

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 one and sell one share of the stock

2013-09-26 00:48:18 3866

原创 LeetCode——Triangle

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], [

2013-09-26 00:41:36 639

原创 LeetCode——Pascal's Triangle II

Given an index k, return the kth row of the Pascal's triangle.For example, given k = 3,Return [1,3,3,1].Note:Could you optimize your algorithm to use only O(k) extra space?» Solve

2013-09-26 00:07:51 639

原创 LeetCode——Pascal's Triangle

Given numRows, generate the first numRows of Pascal's triangle.For example, given numRows = 5,Return[ [1], [1,1], [1,2,1], [1,3,3,1], [1,4,6,4,1]]» Solve this proble

2013-09-25 23:54:45 612

原创 LeetCode——Populating Next Right Pointers in Each Node II

Follow up for problem "Populating Next Right Pointers in Each Node".What if the given tree could be any binary tree? Would your previous solution still work?Note:You may only use constan

2013-09-25 23:43:35 1195

原创 LeetCode——Populating Next Right Pointers in Each Node

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

2013-09-25 20:08:40 1236

原创 LeetCode——Distinct Subsequences

Given 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 deleting some (can be n

2013-09-25 16:50:55 1251

原创 LeetCode——Flatten Binary Tree to Linked List

Given a binary tree, flatten it to a linked list in-place.For example,Given 1 / \ 2 5 / \ \ 3 4 6The flattened tree should look like: 1

2013-09-22 17:39:28 759

原创 LeetCode——Path Sum II

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, 5 / \

2013-09-22 01:49:19 452

原创 LeetCode——Path Sum

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 tree and sum

2013-09-22 01:43:39 782

原创 LeetCode——Partition List

Given a linked list and a value x, partition it such that all nodes less than x come before nodes greater than or equal tox.You should preserve the original relative order of the nodes in each o

2013-09-22 01:37:49 402

原创 LeetCode——Minimum Depth of Binary Tree

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.» Solve this problem/** *

2013-09-22 01:25:43 417

原创 LeetCode——Balanced Binary Tree

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 ofevery node never diff

2013-09-22 01:22:08 1907

原创 LeetCode——Convert Sorted List to Binary Search Tree

Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST.» Solve this problem采用了一种很笨的方法。每次都遍历到中间那个node，然后分左右。/** * Definition f

2013-09-22 01:21:09 441

原创 LeetCode——Convert Sorted Array to Binary Search Tree

Given an array where elements are sorted in ascending order, convert it to a height balanced BST.» Solve this problem每次对半分。/** * Definition for binary tree * struct TreeNode { *

2013-09-22 00:41:46 359

原创 LeetCode——Convert Sorted Array to Binary Search Tree

每次对半分。/** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; *

2013-09-22 00:41:14 81

原创 LeetCode——Binary Tree Level Order Traversal II

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,#,#,15,7}

2013-09-22 00:32:49 1097

原创 LeetCode——Construct Binary Tree from Inorder and Postorder Traversal

Given inorder and postorder traversal of a tree, construct the binary tree.Note:You may assume that duplicates do not exist in the tree.» Solve this problem/** * Definition for bina

2013-09-22 00:19:46 860

原创 LeetCode——Construct Binary Tree from Preorder and Inorder Traversal

Given preorder and inorder traversal of a tree, construct the binary tree.Note:You may assume that duplicates do not exist in the tree.» Solve this problem/** * Definition for binar

2013-09-22 00:14:32 1562

原创 LeetCode——Maximum Depth of Binary Tree

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.» Solve this problem/** *

2013-09-21 23:59:26 673

原创 LeetCode——Binary Tree Zigzag Level Order Traversal

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:Given binar

2013-09-21 23:56:39 356

原创 LeetCode——Binary Tree Level Order Traversal

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}, 3 / \ 9 20

2013-09-21 22:04:28 477

原创 LeetCode——Symmetric Tree

Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).For example, this binary tree is symmetric: 1 / \ 2 2 / \ / \3 4 4 3But the f

2013-09-21 21:38:18 780

原创 LeetCode——Same Tree

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.» Solve th

2013-09-21 21:14:18 495

原创 LeetCode——Recover Binary Search Tree

Two elements of a binary search tree (BST) are swapped by mistake.Recover the tree without changing its structure.Note:A solution using O(n) space is pretty straight forward. Could you devis

2013-09-21 21:13:03 956

原创 LeetCode——Validate Binary Search Tree

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's key.

2013-09-21 17:11:23 799

原创 LeetCode——Interleaving String

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",

2013-09-21 16:39:53 1711

原创 LeetCode——Unique Binary Search Trees II

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. 1

2013-09-21 15:58:50 1310