Tingmei-优快云博客

原创 LeetCode: Valid Number

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

2012-11-05 14:21:31 1294

原创 LeetCode: Trapping Rain Water

Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after raining.For example, Given [0,1,0,2,1,0,1,3,2,1,2,

2012-11-05 14:21:22 934

原创 LeetCode: Substring with Concatenation of All Words

You are given a string, S, and a list of words, L, that are all of the same length. Find all starting indices of substring(s) in S that is a concatenation of each word in L exactly once and withou

2012-11-05 14:21:14 1703

原创 LeetCode: Simplify Path

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

2012-11-05 14:21:03 1131

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 / \

2012-11-05 14:20:43 1918

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

2012-11-05 14:20:34 2998

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./** * Definition for binary tre

2012-11-05 14:20:17 2147

原创 LeetCode: Median of Two Sorted Arrays

There are two sorted arrays A and B of size m and n respectively. Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)).#define INT_MIN 0X80000000#def

2012-11-05 14:15:57 1669

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:

2012-11-05 14:11:46 1370

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

2012-10-09 19:40:27 2300

原创 LeetCode: Longest Palindromic Substring

Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring.O(n^2)的方法：44 milli

2012-10-09 19:39:53 1450

原创 LeetCode: 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.Follow up:Did you use extra space?A straight forward solution using O(mn) space is probably

2012-10-09 00:10:37 1056

原创 LeetCode: 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 target is in t

2012-10-09 00:10:13 1421

原创 LeetCode: Search in Rotated Sorted Array

Suppose a sorted array is rotated at some pivot unknown to you beforehand.(i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2).You are given a target value to search. If found in the array ret

2012-10-09 00:10:04 1105

原创 LeetCode: Wildcard Matching

Implement wildcard pattern matching with support for '?' and '*'.'?' Matches any single character.'*' Matches any sequence of characters (including the empty sequence).The matching should cover t

2012-10-09 00:09:39 3739

原创 LeetCode: Regular Expression Matching

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 entire input st

2012-10-09 00:09:30 10732

原创 LeetCode: Roman to Integer

Given a roman numeral, convert it to an integer.Input is guaranteed to be within the range from 1 to 3999.class Solution {public: int map(char c) { switch(c) {

2012-10-09 00:09:19 1233

原创 LeetCode: Reverse Nodes in k-Group

Given a linked list, reverse the nodes of a linked list k at a time and return its modified list.If the number of nodes is not a multiple of k then left-out nodes in the end should remain as i

2012-10-09 00:09:02 2224

原创 LeetCode: 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", "255.255.111.35"]. (Orde

2012-10-09 00:08:29 1229

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

2012-10-09 00:07:09 2304

原创 LeetCode: 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):"123""132""2

2012-10-09 00:05:58 2667 2

原创 LeetCode: Next Permutation

Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers.If such arrangement is not possible, it must rearrange it as the lowest possible

2012-10-09 00:05:27 2048

原创 LeetCode: N-Queens II

Follow up for N-Queens problem.Now, instead outputting board configurations, return the total number of distinct solutions.递归解法：class Solution {public: bool check(int row, int*

2012-10-09 00:04:48 1357

原创 LeetCode: N-Queens

The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other.Given an integer n, return all distinct solutions to the n-queens

2012-10-09 00:04:19 1270

原创 LeetCode: 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"Minimum window is "BAN

2012-10-09 00:03:29 1941

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

2012-10-08 17:00:23 2259

原创 LeetCode: 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.卡特兰数。class Solution {publi

2012-10-08 16:57:42 1441

原创 LeetCode: 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 1->4->3->2->5->NULL.Note:Given m, n satis

2012-10-08 16:38:11 1161

原创 LeetCode: 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:[ [ 1, 2, 3 ], [ 8, 9, 4 ]

2012-10-08 16:00:10 1004

原创 LeetCode: 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 ], [ 4, 5, 6 ], [ 7, 8, 9 ]]

2012-10-08 15:50:08 1211

原创 LeetCode: Valid Parentheses

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 all va

2012-10-08 15:18:44 654

原创 LeetCode: Swap Nodes in Pairs

Given a linked list, swap every two adjacent nodes and return its head.For example,Given 1->2->3->4, you should return the list as 2->1->4->3.Your algorithm should use only constant space.

2012-10-08 15:04:40 813

原创 LeetCode: Permutations II

Given a collection of numbers that might contain duplicates, return all possible unique permutations.For example,[1,1,2] have the following unique permutations:[1,1,2], [1,2,1], and [2,1,1

2012-10-08 14:35:03 1068

原创 LeetCode: Permutations

Given a collection of numbers, return all possible permutations.For example,[1,2,3] have the following permutations:[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1].class Solut

2012-10-08 14:26:30 1241

原创 LeetCode: Subsets II

Given a collection of integers that might contain duplicates, S, return all possible subsets.Note:Elements in a subset must be in non-descending order.The solution set must not contain

2012-10-08 14:15:15 900

原创 LeetCode: Subsets

Given a set of distinct integers, S, return all possible subsets.Note:Elements in a subset must be in non-descending order.The solution set must not contain duplicate subsets.F

2012-10-08 14:04:49 1533

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 ke

2012-10-08 13:44:59 945

原创 LeetCode: 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 respectively in the

2012-10-08 13:29:25 905

原创 LeetCode: Unique Paths

A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below).The robot can only move either down or right at any point in time. The robot is trying to reach th

2012-10-08 13:28:39 880

原创 LeetCode: Search Insert Position

Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.You may assume no duplicates in the array.

2012-10-08 12:17:18 1198