jeason29-优快云博客

原创 Additive number

Additive number is a positive integer whose digits can form additive sequence.A valid additive sequence should contain at least three numbers. Except for the first two numbers, each subsequent num

2015-11-18 20:33:44 564

原创 Same Tree

Same TreeSep 3 '12Given 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

2015-11-16 20:05:57 354

原创 Range Sum Query 2D - Immutable

Given a 2D matrix matrix, find the sum of the elements inside the rectangle defined by its upper left corner (row1, col1) and lower right corner (row2, col2).The above rectangle (with the red bo

2015-11-15 18:03:47 386

原创段错误调试

我们在用C/C++语言写程序的时侯，内存管理的绝大部分工作都是需要我们来做的。实际上，内存管理是一个比较繁琐的工作，无论你多高明，经验多丰富，难免会在此处犯些小错误，而通常这些错误又是那么的浅显而易于消除。但是手工“除虫”（debug），往往是效率低下且让人厌烦的，本文将就"段错误"这个内存访问越界的错误谈谈如何快速定位这些"段错误"的语句。下面将就以下的一个存在段错误的程序介绍几种调试方

2015-11-12 10:46:28 808

原创 Wildcard Matching

isMatch("aa","a") → falseisMatch("aa","aa") → trueisMatch("aaa","aa") → falseisMatch("aa", "*") → trueisMatch("aa", "a*") → trueisMatch("ab", "?*") → trueisMatch("aab", "c*a*b") → falsebool

2015-11-10 20:06:33 328

原创 Range Sum Query - Immutable

Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive.Example:Given nums = [-2, 0, 3, -5, 2, -1]sumRange(0, 2) -> 1sumRange(2, 5) -> -1sumRan

2015-11-10 20:00:52 423

转载 LeetCode-Valid Number - 有限状态机

判断合法数字用有限状态机，非常简洁，不需要复杂的各种判断！先枚举一下各种合法的输入情况：1.空格+ 数字 +空格2.空格+ 点 + 数字 +空格3.空格+ 符号 + 数字 +　空格4.空格 + 符号 + 点 +　数字　＋空格5.空格 + (1, 2, 3, 4） + e +　(1, 2, 3, 4) +空格组后合法的字符可以是：

2015-11-05 17:48:22 316

原创 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",

2015-11-04 20:31:09 290

原创 Palindrome Partitioning I,II(DFS,DP)

分析：题意给我们一个字符串，求出所有这个字符串的子串，并且子串都为回文字符串的情况，输出它的集合结果解题思路：（跟DFS深度遍历有点像!）字符串Str = "aab";分析了题目的数据之后，我们知道它的结果，可能是 a, a, b 或者 aa, b 这样的情况！也就是说，我们需要去考虑 i = 1, 2 .... n 的情况，比如Str = "

2015-11-04 20:28:10 285

原创 Maximal Square

Given a 2D binary matrix filled with 0's and 1's, find the largest square containing all 1's and return its area.For example, given the following matrix:1 0 1 0 01 0 1 1 11 1 1 1 11 0 0 1 0

2015-11-03 21:59:11 281

原创 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], [

2015-11-01 19:22:03 300

原创 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.

2015-10-29 17:40:45 226

原创 ZigZag Conversion

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 fixed font for better legibility)P A H NA P L S I

2015-10-28 20:21:49 295

原创栈与队列相互实现

用两个队列模拟一个堆栈：队列a和b（1）取栈顶元素：返回有元素的队列的首元素（2）判栈空：若队列a和b均为空则栈空（3）入栈：a队列当前有元素，b为空（倒过来也一样）则将需要入栈的元素先放b中，然后将a中的元素依次出列并入列倒b中。（保证有一个队列是空的）（4）出栈：将有元素的队列出列即可。比如先将1插入队a中，现在要将2入栈，则将2

2015-10-27 19:40:22 306

原创 Find Median from Data Stream

这道题的关键在于要维护两个堆，一个大顶堆，一个小顶堆，这样保证在插入的时候就已经是有序的。对于大顶堆，堆顶一定是堆中最大的值。对于小顶堆，堆顶一定是堆中最小的值。现在我们假设一个有序序列，并把这个有序列分为两半，左边一半为较小数，右边一半为较大数。我们把较小数用大顶堆存储，较大数用小顶堆来存储。那么大顶堆的根一定是较小数里面的最大数，小顶堆的根一定是较大数里面的最小数，也就

2015-10-21 16:56:35 336

原创 merge k sorted lists

Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.solution：快排的思想public class Solution { ListNode merge2Lists(ListNode list1, ListNode list2) {

2015-10-20 15:29:20 258

原创 Lowest Common Ancestor of a Binary Tree

Lowest Common Ancestor of a Binary TreeGiven a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree.According to the definition of LCA on Wikipedia: “The lowest co

2015-10-19 16:25:32 264

原创 DFS之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"]. (Order

2015-10-17 18:08:31 304

You are playing the following Nim Game with your friend: There is a heap of stones on the table, each time one of you take turns to remove 1 to 3 stones. The one who removes the last stone will be the

2015-10-16 17:01:33 254

原创 DFS求回文串

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","

2015-10-15 10:11:36 379

原创 Search for a Range

Given a sorted array of integers, find the starting and ending position of a given target value.Your algorithm's runtime complexity must be in the order of O(log n).If the target is not found

2015-10-15 09:49:56 302

原创数组第k大的数

快排的思想：class Solution {public: int findKthLargest(vector& nums, int k) { int L = 0, R = nums.size() - 1; while (L < R) { int left = L, right = R; int key

2015-10-14 19:42:48 441

原创 Combination Sum III

Find all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be a unique set of numbers.Ensure that numbers wi

2015-10-13 14:52:22 350

转载 DFS经典组合问题

下面将遇到的可以用递归求解的问题归纳于此1. CombinationGiven 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

2015-10-12 15:35:43 753

原创卡特兰数类似问题通解

描述：给定一个非负整数n，生成n对括号的所有合法排列。解答：该问题解的个数就是卡特兰数，但是现在不是求个数，而是要将所有合法的括号排列打印出来。该问题和《编程之美》的买票找零问题一样，通过买票找零问题我们可以知道，针对一个长度为2n的合法排列，第1到2n个位置都满足如下规则：左括号的个数大于等于右括号的个数。所以，我们就可以按照这个规则去打印括号：假设在位置k

2015-10-12 10:52:39 435

原创走格子经典题

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 the

2015-10-12 10:39:02 1598

原创 Maximum Subarray

int max(int a,int b){ return a>=b?a:b;}int maxSubArray(int* nums, int numsSize) { int sum = nums[0] , maxSum = nums[0]; int i=0; for(i = 1; i < numsSize; i++){ if(sum < 0) sum

2015-10-10 16:31:53 294

原创 long long 与 _int64使用总结

在16位环境下，int/unsigned int 占16位，long/unsignedlong占32位，在32位环境下，int占32位，unsigned int占16位，long/unsignedlong占32位何时需要使用：　　long 和 int 范围是[-2^31,2^31)，即-2147483648~2147483647，而unsigned范围是[0,2^32)，即0~429496

2015-10-10 15:51:32 860

原创 Compare Version Numbers

Compare two version numbers version1 and version1.If version1 > version2 return 1, if version1 version2 return -1, otherwise return 0.You may assume that the version strings are non-empty and

2015-10-09 09:07:52 278

原创 Word Pattern

Given a pattern and a string str, find if str follows the same pattern.Examples:pattern = "abba", str = "dog cat cat dog" should return true.pattern = "abba", str = "dog cat cat fish"

2015-10-08 08:47:43 369

原创 Find the Duplicate Number

Given an array nums containing n + 1 integers where each integer is between 1 and n (inclusive), prove that at least one duplicate element must exist. Assume that there is only one duplicate number,

2015-09-28 15:27:20 850

原创两个排序数组第k大的数

double findKth(int a[], int m, int b[], int n, int k){ //always assume that m is equal or smaller than n if (m > n) return findKth(b, n, a, m, k); if (m == 0) return b[k -

2015-09-25 12:06:14 936

原创 Valid Phone Numbers

题目描述：Given a text file file.txt that contains list of phone numbers (one per line), write a one liner bash script to print all valid phone numbers.You may assume that a valid phone number must

2015-09-23 10:00:41 408

原创 move zeros

solution1：双指针思路，遍历一次class Solution {public: void moveZeroes(vector& nums) { int i=0; //Not Zero int j=0; //Zero int l=nums.size(); while(j<l && nums[j]!=0)

2015-09-22 11:54:12 601

原创 Kth Smallest Element in a BST

题目描述：Given a binary search tree, write a function kthSmallest to find the kth smallest element in it.Note:You may assume k is always valid, 1 ≤ k ≤ BST's total elements.Follow up:W

2015-09-22 09:11:35 335

原创翻转二叉树

nvert a binary tree. 4 / \ 2 7 / \ / \1 3 6 9to 4 / \ 7 2 / \ / \9 6 3 1Trivia:This problem was inspired by this original tweet by Max Howel

2015-09-22 08:59:42 395

原创在数组中找到出现频率大于1/4的数

算法的核心思想很简单，每次删去不同的4个数，最后剩下的元素有可能是频繁项。假设数组有15个元素，若一个元素的出现频率大于1/4，其必须出现4次。不妨设数组为{1,2,1,4,1,4,2,9,1,7,4,3,9,4,3}，d表示删去该数。我们来模拟一下算法的过程。第一次 1d,2d,1,4d,1,4,2,9d,1,7,4,3,9,4,3 剩下 1,1,4,2,1,7,4,3,9,4,

2015-09-17 09:04:27 930

原创 Lowest Common Ancestor of a Binary Search Tree (BST)

Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST.According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined betwee

2015-09-16 14:52:03 350

原创 Product of Array Except Self

Given an array of n integers where n > 1, nums, return an array output such that output[i] is equal to the product of all the elements of nums except nums[i].Solve it without division and in O

2015-09-16 14:40:50 385

转载子树判断

//遍历Tree1,查找与Tree2 root相同的节点 boolean HasSubtree(TreeNode root1, TreeNode root2){ boolean result = false; if(root1 != null && root2 != null){ if(root1.val == root2.val){

2015-09-16 13:22:42 437

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