判断一个整数是否是回文数。回文数是指正序（从左向右）和倒序（从右向左）读都是一样的整数。 示例 1: 输入: 121 输出: true示例 2: 输入: -121 输出: false 解释: 从左向右读, 为 -121 。 从右向左读, 为 121- 。因此它不是一个回文数。示例 3: 输入: 10 输出: false 解释: 从右向左读, 为 01 。因此它不是一个回文数。进阶: 你能不将整数转为字符串来解决这个问题吗？class Solution:def isPalindrome(self, x):""":type x: int...
We are given two sentences A and B. (A sentence is a string of space separated words. Each word consists only of lowercase letters.) A word is uncommon if it appears exactly once in one of the sentences, and does not appear in the other sentence. Return a list of all uncommon words. You may return the list in any order. Example 1: Input: A = "this apple is sweet", B = "this apple is sour" Outp...
题目： 判断一个 9x9 的数独是否有效。只需要根据以下规则，验证已经填入的数字是否有效即可。 数字 1-9 在每一行只能出现一次。 数字 1-9 在每一列只能出现一次。 数字 1-9 在每一个以粗实线分隔的 3x3 宫内只能出现一次。上图是一个部分填充的有效的数独。 数独部分空格内已填入了数字，空白格用 '.' 表示。 示例 1:输入: [["5","3",".",".","7",".",".",".","."],["6",".",".","1","9","5",".",".","."],[".","9","8",".",".","...
141环形链表 方法一：快慢指针。 分析：很显然，答案有两种情况，有环，无环。分别设置快慢指针，有环：必然相交，返回True，无环：快指针指向NULL,返回False。 class Solution(object):def hasCycle(self, head):""":type head: ListNode:rtype: bool"""if head == None:return Falselow = headhigh = headwhile high != None and high.next != None: #这里应该是and,注意这里的判断顺序不能改变low = low.next high = high.next...
作者： 负雪明烛 id： fuxuemingzhu 个人博客： http://fuxuemingzhu.cn/题目地址: https://leetcode.com/problems/complete-binary-tree-inserter/description/ 题目描述： A complete binary tree is a binary tree in which every level, except possibly the last, is completely filled, and all nodes are as far left as possible. Write a data structure CBTInserter that is initialized with a complete binary tr...
Given a string S, return the "reversed" string where all characters that are not a letter stay in the same place, and all letters reverse their positions. ?Example 1: Input: "ab-cd" Output: "dc-ba" Example 2: Input: "a-bC-dEf-ghIj" Output: "j-Ih-gfE-dCba" Example 3: Input: "Test1ng-Leet=code-Q!" Output: "Qedo1ct-eeLg=ntse-T!" Note:S.length <= 100 33 <= S[i].ASCIIcode <= 122 S doesnt contain \ o...
给定一种 pattern(模式) 和一个字符串 str ，判断 str 是否遵循相同的模式。 这里的遵循指完全匹配，例如， pattern 里的每个字母和字符串 str 中的每个非空单词之间存在着双向连接的对应模式。 示例1:输入: pattern = "abba", str = "dog cat cat dog" 输出: true 示例 2:输入:pattern = "abba", str = "dog cat cat fish" 输出: false 示例 3:输入: pattern = "aaaa", str = "dog cat cat dog" 输出: false 示例 4:输入: pattern...
Given two binary trees and imagine that when you put one of them to cover the other, some nodes of the two trees are overlapped while the others are not. You need to merge them into a new binary tree. The merge rule is that if two nodes overlap, then sum node values up as the new value of the merged node. Otherwise, the NOT null node will be used as the node of new tree. Example 1: Input: Tree 1 ...
参考资料： 1、《面试算法LeetCode刷题班》 - 小象学院 2、csujedihy /?lc-all-solutions 一、链表 1. 链表的必备知识要点(包括基础知识、刷题中使用的STL等知识) 2. 链表逆序(LeetCode 92 ,206. Reverse Linked List 1,2) 3. 求两个链表的交点(LeetCode 160. Intersection of Two Linked Lists) 4. 链表的节点交换(LeetCode 24. Swap Nodes in Pairs) 5. 链表求环(LeetCode 141 ,142. Linked Lis...
Given the root node of a binary search tree (BST) and a value. You need to find the node in the BST that the nodes value equals the given value. Return the subtree rooted with that node. If such node doesnt exist, you should return NULL. For example, Given the tree:4/ 2 7/ 1 3And the value to search: 2You should return this subtree:2 / \ 1 3In the example above, if we want t...
颠倒给定的 32 位无符号整数的二进制位。 示例:输入: 43261596 输出: 964176192 解释: 43261596 的二进制表示形式为 00000010100101000001111010011100 ， 返回 964176192，其二进制表示形式为 00111001011110000010100101000000 。 进阶: 如果多次调用这个函数，你将如何优化你的算法？ 注意：需要补齐32位 class Solution: # @param n, an integer # @return an integer def reverseBits(self, n): r...
题目： 给定一个数组，它的第 i 个元素是一支给定股票第 i 天的价格。 设计一个算法来计算你所能获取的最大利润。你可以尽可能地完成更多的交易（多次买卖一支股票）。 注意：你不能同时参与多笔交易（你必须在再次购买前出售掉之前的股票）。 示例 1: 输入: [7,1,5,3,6,4] 输出: 7 解释: 在第 2 天（股票价格 = 1）的时候买入，在第 3 天（股票价格 = 5）的时候卖出, 这笔交易所能获得利润 = 5-1 = 4 。 随后，在第 4 天（股票价格...
908. 最小差值 I 题目描述提示帮助提交记录社区讨论阅读解答 随机一题 给定一个整数数组 A，对于每个整数 A[i]，我们可以选择任意 x 满足 -K <= x <= K，并将 x 加到 A[i] 中。 在此过程之后，我们得到一些数组 B。 返回 B 的最大值和 B 的最小值之间可能存在的最小差值。 示例 1：输入：A = [1], K = 0 输出：0 解释：B = [1]示例 2：输入：A = [0,10], K = 2 输出：6 解释：B = [2,8]示例 3：输入：A = [1,3,6], K = 3 输出：0...
作者： 负雪明烛 id： fuxuemingzhu 个人博客： http://fuxuemingzhu.cn/题目地址: https://leetcode.com/problems/minimum-cost-to-hire-k-workers/description/ 题目描述： There are N workers. The i-th worker has a quality[i] and a minimum wage expectation wage[i]. Now we want to hire exactly K workers to form a paid group. When hiring a group of K workers, we must pay them according to the followin...
杨辉三角 一开始自己使用的方法 1 class Solution:2 def generate(self, numRows):3 """4 :type numRows: int5 :rtype: List[List[int]]6 """7 if numRows == 0:8 return []9 elif numRows == 1: 10 return [[1]] 11 elif numRows == 2: 12 return [[1], [1, 1]] 13 else: 14 triangle = [[1],[1,1]] 15 ...