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

题目 Given an array of integers, every element appears three times except for one. Find that single one. Note: Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory? 分析 由上一题改动而来,LeetCode 136 Single Nu…

题目 Write an algorithm to determine if a number is "happy". A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until…

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 partially filled sudoku which is valid. Note: A valid Sudoku board (partia…

Hard! 题目描述: 验证给定的字符串是否为数字. 例如:"0" => true" 0.1 " => true"abc" => false"1 a" => false"2e10" => true 说明: 我们有意将问题陈述地比较模糊.在实现代码之前,你应当事先思考所有可能的情况. 解题思路: 这道验证数字的题比想象中的要复杂的多,有很多情况需要考虑.网上有很多解法,有利用有限…

题目 Additive number is a string whose digits can form additive sequence. A valid additive sequence should contain at least three numbers. Except for the first two numbers, each subsequent number in the sequence must be the sum of the preceding two. Fo…

题目 Given two strings s and t, write a function to determine if t is an anagram of s. For example, s = "anagram", t = "nagaram", return true. s = "rat", t = "car", return false. Note: You may assume the string contai…

题目: 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 valid but "(]" and "([)]&…

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" is not a palindrome. Note: Have you consider t…

题目 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 valid but "(]" and "([)]&q…

题目 Given an array of numbers nums, in which exactly two elements appear only once and all the other elements appear exactly twice. Find the two elements that appear only once. For example: Given nums = [1, 2, 1, 3, 2, 5], return [3, 5]. Note: The ord…

题目 Given an array containing n distinct numbers taken from 0, 1, 2, -, n, find the one that is missing from the array. For example, Given nums = [0, 1, 3] return 2. Note: Your algorithm should run in linear runtime complexity. Could you implement it…

题目 Given an array of integers, every element appears twice except for one. Find that single one. Note: Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory? 分析 给定一个序列 找出只出现一次的元素,其它元素均出现2次: 要求线性时间,不…

题目: Determine whether an integer is a palindrome. Do this without extra space. Some hints: Could negative integers be palindromes? (ie, -1) If you are thinking of converting the integer to string, note the restriction of using extra space. You could…

Leetcode(4)寻找两个有序数组的中位数 [题目表述]: 给定两个大小为 m 和 n 的有序数组 nums1 和* nums2. 请你找出这两个有序数组的中位数,并且要求算法的时间复杂度为 O(log(m + n)). 你可以假设 nums1* 和 nums2 不会同时为空. 第一种方法:list拼接排列取中位数 执行用时:116 ms : 内存消耗:11.8MB 效果:还行 class Solution(object): def findMedianSortedArrays(self,…

Home / Qt 学习之路 2 / Qt 学习之路 2(65):访问网络(1) Qt 学习之路 2(65):访问网络(1)  豆子  2013年10月11日  Qt 学习之路 2  18条评论 现在的应用程序很少有纯粹单机的.大部分为了各种目的都需要联网操作.为此,Qt 提供了自己的网络访问库,方便我们对网络资源进行访问.本章我们将介绍如何使用 Qt 进行最基本的网络访问. Qt 进行网络访问的类是QNetworkAccessManager,这是一个名字相当长的类,不过使用起来并不像它的名字一…

题目 Follow up for H-Index: What if the citations array is sorted in ascending order? Could you optimize your algorithm? 分析 同LeetCode(274)H-Index第二个版本,给定引用数量序列为递增的:这就省略了我们的第一个排序步骤: O(n)的时间复杂度,遍历一次即可. AC代码 class Solution { public: int hIndex(vector<int>…

题目 Given an array of integers, find out whether there are two distinct indices i and j in the array such that the difference between nums[i] and nums[j] is at most t and the difference between i and j is at most k. 分析 题目描述:给定一个整数序列,查找是否存在两个下标分别为i和j的元…

题目 Follow up for "Find Minimum in Rotated Sorted Array": What if duplicates are allowed? Would this affect the run-time complexity? How and why? Suppose a sorted array is rotated at some pivot unknown to you beforehand. (i.e., 0 1 2 4 5 6 7 migh…

题目 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 one and sell one share of the stock multiple times).…

题目 Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; } Populate each next pointer to point to its next right node. If there is no next right node, the next pointer should be set to NULL. Initially,…

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, 分析 本题目与上一题LeetCode(112) Path Sum虽然类型相同,但是需要在以前的基础上,多做处理一些: 与Path Sum相比,本题是求出路径,所以,在找到满足的路…

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,#,#,15,7}, return its bottom-up level order traversal as: 分析 与…

题目 There are two sorted arrays nums1 and nums2 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)). 分析 给定两个有序序列,要求两个序列综合后的中位数.关键:算法复杂度T(n)=O(log(m+n)) 该问题的关键就在于复杂度的限制,有了这个限制,就…

Leetcode(1)两数之和 [题目表述]: 给定一个整数数组 nums 和一个目标值 target,请你在该数组中找出和为目标值的那 两个 整数,并返回他们的数组下标.你可以假设每种输入只会对应一个答案.但是,你不能重复利用这个数组中同样的元素. 第一种方法:暴力 执行用时:5352 ms: 内存消耗:12.9MB 效果:非常差 class Solution(object): def twoSum(self, nums, target): """ :type nums:…

Leetcode(2)两数相加 [题目表述]: 给出两个 非空 的链表用来表示两个非负的整数.其中,它们各自的位数是按照 逆序 的方式存储的,并且它们的每个节点只能存储 一位 数字. 如果,我们将这两个数相加起来,则会返回一个新的链表来表示它们的和.您可以假设除了数字 0 之外,这两个数都不会以 0 开头. 第一种方法:大众解法 执行用时:80 ms: 内存消耗:12.2MB # Definition for singly-linked list. # class ListNode(object…

Leetcode(3)无重复字符的最长子串 [题目表述]: 给定一个字符串,请你找出其中不含有重复字符的 最长子串 的长度. 第一种方法:暴力 执行用时:996 ms: 内存消耗:12.9MB 效果:太差 class Solution(object): def lengthOfLongestSubstring(self, s): """ :type s: str :rtype: int """ Maxsize=0 res='' if len(s)…

Leetcode(4)寻找两个有序数组的中位数 [题目表述]: 给定一个字符串 s,找到 s 中 最长 的回文子串.你可以假设 s 的最大长度为 1000.' 第一种方法:未完成:利用回文子串的特点 一开始我的思路如下:回文子串的特点是首尾字母相同,所以我对每一个字母都找到位于它后面的相同字母,利用切片判断这一段是否为回文子串(str[i:j]==str[i:j][::-1]).时间复杂度很高,主要是因为str.find操作非常耗时. class Solution(object): def lo…

Leetcode(6)Z字形变换 [题目表述]: 将一个给定字符串根据给定的行数,以从上往下.从左到右进行 Z 字形排列. 比如输入字符串为 "LEETCODEISHIRING" 行数为 3 时,排列如下: L C I R E T O E S I I G E D H N 之后,你的输出需要从左往右逐行读取,产生出一个新的字符串,比如:"LCIRETOESIIGEDHN". 第一次:找下标规律按行输出 执行用时:84 ms: 内存消耗:11.8MB 效果:还行 cla…

Leetcode(6)Z字形变换 [题目表述]: 给出一个 32 位的有符号整数,你需要将这个整数中每位上的数字进行反转. 第一次:转字符串处理 执行用时:40 ms: 内存消耗:11.6MB 效果:很好 class Solution(object): def reverse(self, x): """ :type x: int :rtype: int """ if x>=0: r=str(x) r=r[::-1] n=int(r) els…