千寻的专栏

题目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

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题目方法一方法二

题目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 = "a

题目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 us

题目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" i

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题目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]]

题目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

题目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 ent

题目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 =

题目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.方法一后序遍历树，使用递归，

题目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

题目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 t

题目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

题目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.方法使用DFS对树进行遍

题目Implement wildcard pattern matching with support for '?' and '*'.'?' Matches any single character.'*' Matches any sequence of characters (including the empty sequence).The matching sh

题目Given an array where elements are sorted in ascending order, convert it to a height balanced BST.方法数组是有序的，要求创建的二叉树尽量平衡，很容易想到对数组进行二分操作，左边的数组元素是左子树，右边的数组元素是右子树。进行递归操作就可以了。 TreeNode

题目Given inorder and postorder traversal of a tree, construct the binary tree.Note:You may assume that duplicates do not exist in the tree.方法根据树的中序遍历和后序遍历，来恢复树，使用递归的思想。 Tr

题目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:G

题目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 3

题目方法使用递归，先判断当前节点，

题目Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST.方法和有序数组的思想基本一样，将链表进行二分。 TreeNode getBST(ListNode head, int len) { i

题目Given preorder and inorder traversal of a tree, construct the binary tree.Note:You may assume that duplicates do not exist in the tree.方法根据树的中序遍历和前序遍历，来构造树，使用递归的思想。 Tre

题目Given a binary tree, return the inorder traversal of its nodes' values.For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3return [1,3,2].Note: Recur

题目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

题目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. Cou

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题目 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 / \

题目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

题目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.

题目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 = "aadb

题目Given n non-negative integers a1, a2, ..., an, where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of line i is at (i, ai) and (

题目Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules.The Sudoku board could be partially filled, where empty cells are filled with the character '.'.A par

题目Given a string containing only digits, restore it by returning all possible valid IP address combinations.For example:Given "25525511135",return ["255.255.11.135", "255.255.111.3