回文数题目描述：给你一个整数 x ，如果 x 是一个回文整数，返回 true ；否则，返回 false 。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。例如，121 是回文，而 123 不是。示例说明请见LeetCode官网。来源：力扣（LeetCode）链接：https://leetcode-cn.com/probl...著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。解法一：前后遍历如果是负数，直接返回false；否则，将整数转化为字符串...
Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.Note:Elements in a triplet (a,b,c) must be in non-descending order. (ie, a ≤ b ≤ c)The solution set must not contain duplicate triplets. For example, given array S = {-1 0 1 2 -1 -4},A solution set is:(-1, 0, 1)(-1, -1, 2) Have you met this...
地址:https://leetcode.com/problems/two-sum/题意:给定一个数组和一个target, 如果数组中有两个数的和恰好等于target, 返回它们的下标. 题解:思路有很多, 随便搞一搞就可以比如: 先排序, 然后遍历每一个数, 二分查找另一个因为python自带字典树(dist), 所以这里给出更方便的这种做法: 先按照 d = { 值 : 下标 } 建树, 然后遍历每一个数, 直接查找另一个, 返回这两个数的下标即可代码: 1class Solution(object):2def twoSum(sel...
Palindrome NumberDetermine whether an integer is a palindrome. Do this without extra space.click to show spoilers.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 also try reversing an integer. However, if you have solved the problem "Reverse Integer", you know that the reversed ...
编号145：二叉树的后序遍历给定一个二叉树，返回它的 后序 遍历。示例: 输入: [1,null,2,3] 12/3 输出: [3,2,1] 进阶: 递归算法很简单，你可以通过迭代算法完成吗？思路具体代码如下：//Definition for a binary tree node. type TreeNode struct {Val intLeft *TreeNodeRight *TreeNode } 递归算法/*递归三部曲 1.确定递归函数的参数和返回值 2.确定终止条件 3.确定单层递归的逻辑 *///1.确定递归函数的参数和返回值：因为要打...
Implement the following operations of a queue using stacks.push(x) -- Push element x to the back of queue.pop() -- Removes the element from in front of queue.peek() -- Get the front element.empty() -- Return whether the queue is empty.Notes:You must use only standard operations of a stack -- which means only push to top, peek/pop from top, size, and is empty operations are valid.Depending on your ...
颠倒给定的 32 位无符号整数的二进制位进阶: 如果多次调用这个函数，你将如何优化你的算法？address#!/usr/bin/python # -*- coding:utf-8 -*-# 方法1 def reverseBits(n: int) -> int:result = 0for i in range(32):# 此处+优先符高于&result = (result << 1) + (n & 1)n >>= 1return resultif __name__ == '__main__':message = 43261596print(reverseBits(message))
Given an integer array with even length, where different numbers in this array represent different kinds of candies. Each number means one candy of the corresponding kind. You need to distribute these candies equally in number to brother and sister. Return the maximum number of kinds of candies the sister could gain.Input: candies = [1,1,2,2,3,3] Output: 3 Explanation: There are three different ki...
102. Binary Tree Level Order TraversalGiven 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,null,null,15,7], 3 / 9 20 / 15 7return its level order traversal as:[ [3], [9,20], [15,7] ]解题思路：采用双队列来处理。用当前队列current来处理本层的所有节点，将本层信息记录在vector中...
Well, the basic idea is fairly straightforward. We maintain a mapping mp from a value in nums to its position (index) i. Each time we meet an unseen value, we add it to the map (mp[nums[i]] = i). Otherwise, depending on whether the recorded index mp[nums[i]] and the current index isatisfy i - mp[nums[i]] <= k (node that the new index i is larger than the old indexmp[nums[i]]), we return true or up...
这道题思路很简单，就是在一个loop下找最大的和第二大的数值。记住，python最小的数值是-sys.maxsize-1class Solution:def dominantIndex(self, nums: List[int]) -> int:ifnot nums or len(nums) == 1:return 0largest, sec_largest, idx = -sys.maxsize - 1, -sys.maxsize - 1, 0for i in range(len(nums)):if nums[i] >= largest: sec_largest = largestlargest = nums[i] idx = iif nums[i] > sec_largest and nums[i] < larg...
有 n 个气球，编号为0 到 n-1，每个气球上都标有一个数字，这些数字存在数组 nums 中。现在要求你戳破所有的气球。每当你戳破一个气球 i 时，你可以获得 nums[left] * nums[i] * nums[right] 个硬币。 这里的 left 和 right 代表和 i 相邻的两个气球的序号。注意当你戳破了气球 i后，气球 left 和气球 right 就变成了相邻的气球。求所能获得硬币的最大数量。说明:你可以假设 nums[-1] = nums[n] = 1，但注意它们不是真实存在的所以...
263. 丑数 Difficulty: 简单 给你一个整数 n ，请你判断 n 是否为 丑数 。如果是，返回 true ；否则，返回 false 。 丑数 就是只包含质因数 2、3 和/或 5 的正整数。 示例 1： 输入：n = 6 输出：true 解释：6 = 2 × 3示例 2： 输入：n = 8 输出：true 解释：8 = 2 × 2 × 2示例 3： 输入：n = 14 输出：false 解释：14 不是丑数，因为它包含了另外一个质因数?7 。示例 4： 输入：n = 1 输出：true 解释：1 通常被视为丑数。提示：-...
一直以来学习的都是些理论，编程一直用的也是MATLAB，其他语言很少涉及。希望自己弥补这一块短板，时间初步定在五月底，拿出半个月时间学习Python，学多少算多少。直接从leetcode开始： 原文：http://www.cnblogs.com/xingshansi/p/6858974.html
Given two binary strings, return their sum (also a binary string). For example, a = "11" b = "1"Return "100".这道也是水题，但是注意有前导0，还有全0的时候输出为0。.还有最后结果的处理。#include <iostream> #include <string>using namespace std;class Solution { public:string addBinary(string a, string b) {if (a.empty()){return b;}if (b.empty()){return a;}int i = 0;int j = 0;for (; i < a.size(); ++i){if...