leedcode

[leedcode 106] 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. /** * Definition for a binary tree node. * public class
·2015-10-21 12:55

[leedcode 102] 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 / \
·2015-10-21 12:54

[leedcode 104] 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. /** * Definition for a binary tree
·2015-10-21 12:54

[leedcode 152] Maximum Product Subarray

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 t
·2015-10-21 12:54

[leedcode 103] 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 b
·2015-10-21 12:54

[leedcode 100] 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. /** * Defin
·2015-10-21 12:53

[leedcode 99] 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 devise a co
·2015-10-21 12:53

[leedcode 101] 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 3   But
·2015-10-21 12:53

[leedcode 96] 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 be
·2015-10-21 12:51

[leedcode 95] Unique Binary Search Trees

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
·2015-10-21 12:51

[leedcode 98] 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
·2015-10-21 12:51

[leedcode 97] 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&quo
·2015-10-21 12:51

[leedcode 93] Restore IP Addresses

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", &q
·2015-10-21 12:49

[leedcode 91] Decode Ways

A message containing letters from A-Z is being encoded to numbers using the following mapping: 'A' -> 1 'B' -> 2 ... 'Z' -> 26 Given an encoded message containing digits, det
·2015-10-21 12:49

[leedcode 94] Binary Tree Inorder Traversal

Given a binary tree, return the inorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3   return [1,3,2]. Note
·2015-10-21 12:49

[leedcode 92] Reverse Linked List II

Reverse a linked list from position m to n. Do it in-place and in one-pass. For example:Given 1->2->3->4->5->NULL, m = 2 and n = 4, return 
·2015-10-21 12:49

[leedcode 90] Subsets II

Given a collection of integers that might contain duplicates, nums, return all possible subsets. Note: Elements in a subset must be in non-descending order. The solution set must not conta
·2015-10-21 12:47

[leedcode 88] Merge Sorted Array

Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array. Note:You may assume that nums1 has enough space (size that is
·2015-10-21 12:46

[leedcode 89] Gray Code

The 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 code, print the sequ
·2015-10-21 12:46

[leedcode 87] Scramble String

Given a string s1, we may represent it as a binary tree by partitioning it to two non-empty substrings recursively. Below is one possible representation of s1 = "great":
·2015-10-21 12:45

[leedcode 80] Remove Duplicates from Sorted Array II

Follow up for "Remove Duplicates":What if duplicates are allowed at most twice? For example,Given sorted array nums = [1,1,1,2,2,3], Your function should return length
·2015-10-21 12:44

[leedcode 81] Search in Rotated Sorted Array II

Follow up for "Search in Rotated Sorted Array":What if duplicates are allowed? Would this affect the run-time complexity? How and why? Write a function to determine if a given ta
·2015-10-21 12:44

[leedcode 82] Remove Duplicates from Sorted List II

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,
·2015-10-21 12:44

[leedcode 83] Remove Duplicates from Sorted List

Given a sorted linked list, delete all duplicates such that each element appear only once. For example,Given 1->1->2, return 1->2.Given 1->1->2->3->3, return&
·2015-10-21 12:44

[leedcode 79] Word Search

Given a 2D board and a word, find if the word exists in the grid. The word can be constructed from letters of sequentially adjacent cell, where "adjacent" cells are those horizontally or ve
·2015-10-21 12:42

[leedcode 78] Subsets

Given a set of distinct integers, nums, return all possible subsets. Note: Elements in a subset must be in non-descending order. The solution set must not contain duplicate subsets. &nb
·2015-10-21 12:42

[leedcode 77] Combinations

Given two integers n and k, return all possible combinations of k numbers out of 1 ... n. For example,If n = 4 and k = 2, a solution is: [ [2,4],
·2015-10-21 12:41

[leedcode 75] Sort Colors

Given an array with n objects colored red, white or blue, sort them so that objects of the same color are adjacent, with the colors in the order red, white and blue. Here, we will use the i
·2015-10-21 12:40

[leedcode 74] Search a 2D Matrix

Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:   Integers in each row are sorted from left to right.
·2015-10-21 12:39

[leedcode 73] Set Matrix Zeroes

Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in place. public class Solution { public void setZeroes(int[][] matrix) { //题目要求
·2015-10-21 12:39

[leedcode 76] Minimum Window Substring

Given 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 = "ADOBECODEBANC"T = "ABC
·2015-10-21 12:39

[leedcode 71] Simplify Path

Given an absolute path for a file (Unix-style), simplify it. For example,path = "/home/", => "/home"path = "/a/./b/../../c/", => &quo
·2015-10-21 12:38

[leedcode 70] Climbing Stairs

You 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? public class Solution
·2015-10-21 12:37

[leedcode 69] Sqrt(x)

Implement int sqrt(int x). Compute and return the square root of x. public class Solution { //本题利用了牛顿迭代法：设r是f(x) = 0的根（x^2-k=f(x)），选取x0作为r初始近似值，过点（x0,f(x0)）做曲线y = f(x)的切线L，L的方程为y = f
·2015-10-21 12:37

[leedcode 67] Add Binary

Given two binary strings, return their sum (also a binary string). For example,a = "11"b = "1"Return "100". public class Solution { public String a
·2015-10-21 12:37

[leedcode 66] Plus One

Given a non-negative number represented as an array of digits, plus one to the number. The digits are stored such that the most significant digit is at the head of the list. public class Solution {
·2015-10-21 12:36

[leedcode 65] Valid Number

Validate if a given string is numeric. Some examples:"0" => true" 0.1 " => true"abc" => false"1 a" => false
·2015-10-21 12:35

[leedcode 64] Minimum Path Sum

Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path. Note: You can
·2015-10-21 12:35

[leedcode 60] Permutation Sequence

The 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, for n = 3): &q
·2015-10-21 12:34

[leedcode 59] Spiral Matrix II

Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order. For example,Given n = 3, You should return the following matrix: [ [
·2015-10-21 12:34

[leedcode 61] Rotate List

Given a list, rotate the list to the right by k places, where k is non-negative. For example:Given 1->2->3->4->5->NULL and k = 2,return&nbs
·2015-10-21 12:34

[leedcode 63] Unique Paths II

Follow up for "Unique Paths": Now consider if some obstacles are added to the grids. How many unique paths would there be? An obstacle and empty space is marked as 1 and 0&n
·2015-10-21 12:34

[leedcode 54] Spiral Matrix

Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order. For example,Given the following matrix: [ [ 1, 2, 3 ],
·2015-10-21 12:33

[leedcode 58] Length of Last Word

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:&
·2015-10-21 12:33

[leedcode 57] Merge Intervals

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. * public
·2015-10-21 12:33

[leedcode 53] Maximum Subarray

Find the contiguous subarray within an array (containing at least one number) which has the largest sum. For example, given the array [−2,1,−3,4,−1,2,1,−5,4],the contiguous subarray [4,−1,2
·2015-10-21 12:32

[leedcode 121] 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 o
·2015-10-21 10:17

[leedcode 120] 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], [6
·2015-10-21 10:16

[leedcode 119] 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]. public class Solution { public List<Integer> getRo
·2015-10-21 10:16

[leedcode 118] 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] ]
·2015-10-21 10:15
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