LouisLan的学习简记 👋🏼

题目地址 https://leetcode.com/problems/longest-palindromic-substring/description/ 题目描述 Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000. Example 1: Input: "babad" Output: "bab" Note: "aba" is also a valid answer. Example 2: Input: "cbbd" Output: "bb" 思路 这是一道最长回文的题目，要我们求出给定字符串的最大回文子串。 解决这类问题的核心思想就是两个字“延伸”，具体来说 如果一个字符串是回文串，那么在它左右分别加上一个相同的字符，那么它一定还是一个回文串 如果一个字符串不是回文串，或者在回文串左右分别加不同的字符，得到的一定不是回文串 事实上，上面的分析已经建立了大问题和小问题之间的关联， 基于此，我们可以建立....

题目地址 https://leetcode.com/problems/median-of-two-sorted-arrays/ 题目描述 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)). You may assume nums1 and nums2 cannot be both empty. Example 1: nums1 = [1, 3] nums2 = [2] The median is 2.0 Example 2: nums1 = [1, 2] nums2 = [3, 4] The median is (2 + 3)/2 = 2.5 思路 首先了解一下 Median 的概念，一个数组中 median 就是把数组分成左右等分的中位数。 如下图： 这道题，很容易想到暴力解法，时间复杂度和空....

题目地址 https://leetcode.com/problems/longest-substring-without-repeating-characters/ 题目描述 Given a string, find the length of the longest substring without repeating characters. Example 1: Input: "abcabcbb" Output: 3 Explanation: The answer is "abc", with the length of 3. Example 2: Input: "bbbbb" Output: 1 Explanation: The answer is "b", with the length of 1. Example 3: Input: "pwwkew" Output: 3 Explanation: The answer is "wke", with the length of 3. Note that the answer must be a substring, "pw....

题目地址 https://leetcode.com/problems/add-two-numbers/ 题目描述 You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list. You may assume the two numbers do not contain any leading zero, except the number 0 itself. Example: Input: (2 -> 4 -> 3) + (5 -> 6 -> 4) Output: 7 -> 0 -> 8 Explanation: 342 + 465 = 807. 思路 这道并不是什么难题，算法很....

题目地址 https://leetcode.com/problems/two-sum 题目描述 Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one solution, and you may not use the same element twice. Example: Given nums = [2, 7, 11, 15], target = 9, Because nums[0] + nums[1] = 2 + 7 = 9, return [0, 1]. 思路 开启 LeetCode 刷题的旅程，这将是一段漫长而又艰辛的旅程，这是一条攀登珠穆朗玛的皑皑雪山路，这是通向 One Piece 宝藏的伟大航路，这是成为火影的无比残酷的修罗场，这是打破吊丝与高富帅之间界限的崩玉。但请不要害怕，在老船长 Grandyang 博....