Programmer Think

📢 preface 🚀 Algorithm problem 🚀 🌲 Punching out an algorithm problem every day is not only a learning process, but also a sharing process 😜🌲 Tip: the problem-solving programming languages in this column are C# and Java🌲 To maintain a state of learning every day, let's work together to become the great God of algorithm ...

1. Question 5 of the longest palindrome substring force deduction Substring: substring must be continuous, which is different from the concept of subsequence Subsequence: Where the violent solution can be optimized: palindromes are judged only when the length of the substring is > the current maximum length, Is there anything that can be ...

Breadth first search traversal, also known as BFS, belongs to blind search method. It is one of the search algorithms of graph. The purpose is to systematically expand and check all nodes in the graph to find results. In other words, it does not consider the possible location of the result and searches the whole graph thoroughly until it finds ...

1. Where the dream begins - the 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 the array cannot be r ...

3. Longest string without duplicate characters Method 1. Violence solution Generate substrings one by one See if it does not contain duplicate characters Method 2. Sliding window and optimization Do not repeat from a to C. when a repeats, the left pointer moves one bit to the right The right pointer moves one bit to the right Double pointer JA ...

Binary search Binary search Given an n-element ordered (ascending) integer array nums and a target value target, write a function to search the target in nums. If the target value exists, return the subscript, otherwise return - 1. Example 1: Input: num = [- 1,0,3,5,9,12], target = 9, output: 4 Explanation: 9 appears in nums and the sub ...

93. Restore IP address LeetCode Released: 21:26:11, September 18, 2021 Problem description and examples Given a string containing only numbers to represent an IP address, return all valid IP addresses that may be obtained from s. You can return answers in any order. A valid IP address consists of exactly four integers (each integer is bet ...

43. String multiplication Give two nonnegative integers in string form   num1   and   Num2, return   num1   and   num2   Their products are also expressed in string form. Example 1: Input: num1 = "2", num2 = "3" Output: "6" Example   2: Input: num1 = "123", num ...

Given a different set of words, find all the different index pairs (i, j) so that two words in the list, words[i] + words[j], can be stitched together into palindrome strings. Example 1: Input: words = ["abcd","dcba","lls","s","sssll"] Output:[[0,1],[1,0],[3,2],[2,4]] Interpretation: A spliceable palindrome string is ["dcbaabcd","abcddcba"," ...

189. Medium difficulty: the content refers to the official answer Think of the array as a ring connected end to end. Moving right is equivalent to rotating the ring Requirements: 1. Use the in-situ algorithm with spatial complexity O(1) to solve this problem; 2. There are at least three different ways to solve this problem Problem solving ide ...