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15. Sum of three Link: https://leetcode-cn.com/problems/3sum/ See the link for the title description. Solution 1: triple cycle + HasH de duplication I couldn't think of any good idea, so I started it in a stupid way, compared it with three cycles, saved the existing results with a HasH, and made the first two numbers of the results as ...

1. (Leetcode665) non decreasing column: given an integer array of length N, your task is to judge whether the array can become a non decreasing column when at most one element is changed. We define a non decreasing column as follows: for all I (1 < = I < n) in the array, array [i] < = array [i + 1] is satisfied Idea: Judge whether to ...

1. Valid Letter Words Given two strings s and t, write a function to determine whether t is an alphabetic ectopic word of s. Note: if each character in S and t occurs the same number of times, s and T are called alphabetic words. Valid Letter ectopic words Idea: 1. Create an array with a size of 26 to record the number of occurr ...

Title Link https://leetcode-cn.com/problems/valid-anagram/ Source code github address https://github.com/YIMEng-0/DataStructure 1. Title Requirements Given two strings s and t, write a function to determine whether t is an alphabetic ectopic word of s. Concept of acronym: Note: if each character in S and t occurs the same nu ...

Two dimensional array transformation Remodeling matrix Topic introduction Train of thought analysis This question can be written according to the meaning of the question, but before traversing the two-dimensional array, judge whether the given r and c are reasonable in advance. If not, just return directly.When the product of r and ...

Here is the title: https://leetcode-cn.com/problems/find-majority-element-lcci/ Topic analysis: Be sure to see the problem clearly. In the problem, please design a solution with time complexity of O(N) and space complexity of O(1). Train of thought analysis: This problem is not difficult to understand. Find the element with the most occurre ...

Topic source 208. Implement Trie (prefix tree) Title details Trie (pronounced like "try") or prefix tree is a tree data structure used to efficiently store and retrieve keys in string data sets. This data structure has many application scenarios, such as automatic completion and spell checking. Please implement the Trie class: Trie() ...

JZ86 (m) finds the nearest common ancestor of two nodes in the binary tree Simple idea: first dfs, record the path, find the corresponding value, and then return; Then compare the two paths (arrays) obtained by dfs and find the last same value from scratch;Complexity: time O ...

Li Kou brush question diary [January 19, 2022] 1. Sum of two numbers Given an integer array nums and an integer target value target, please find the two integers with and as the target value target in the array and return their array subscripts. You can assume that each input will correspond to only one answer. However, the same element in th ...

Give you an array num containing n integers. Judge whether there are three elements a, b and c in num, so that a + b + c = 0? Please find all triples with sum 0 and no repetition. Note: the answer cannot contain duplicate triples. Example 1: Input: num = [- 1,0,1,2, - 1, - 4] Output: [- 1, - 1,2], [- 1,0,1]] Example 2: Input: num = [] Output ...