DSA Blind 75 | Problems and solutions

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75 DSA problems topicwise

Given below is a list of popular DSA problems topicwise with solutions.
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Morris Traversal Binary Tree Inorder (without Recursion or Stack)

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Inorder is one of the ways to traverse a binary tree in depth first fashion. We have already discussed Inorder Traversal (Left, Root, Right) of a binary thee in our previous articles using recursive approach and using stack (without recursion). But in this article we will discuss Morris Traversal which is used to traverse a Binary Tree without using recursion or Stack. If you are interested in Inorder traversal using recursion or iterative approach using Stack, refer below articles - Tree Traversal - Depth First (Iterative/ Non Recursive Approach) Tree Traversals - Depth First (Recursive Approach) Explanation Morris Traversal - Suppose we have a binary tree as shown in the figure below. Now we already know that Inorder traversal follows this order - Left, Root, Right. And this sequence must be followed by all the  sub trees  as well. In-order traversal of this Tree would be -  2 3 4 5 6 8 10 In this sequence we can clearly see that after visiting the left node or left sub...
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DSA Array | Valid Anagram

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Problem Statement Write a function that takes two strings, s and t, as input and determines whether they are anagrams of each other. Return true if the two strings are anagrams and false otherwise. An anagram is defined as a string formed by rearranging the characters of another string, using all the original characters exactly once. Example 1: Input: s = "listen", t = "silent" Output: true Explanation: Both strings contain the same characters ('l', 'i', 's', 't', 'e', 'n') in different orders. Example 2: Input: s = "hello", t = "world" Output: false Explanation: The characters in s and t do not match exactly. Code: class Solution { public boolean isAnagram(String s, String t) { Map <Character, Integer> map = new HashMap <> (); int n1 = s.length(); ...
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Spring-Boot externalize logback configuration file (logback-spring.xml)

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Many times there is a need to externalize the logging configuration file in spring boot, so that without making any code level/ jar level changes we can easily change the logging configuration. For example If we deliver any spring boot application as a jar we dont want the logging file name to be hardcoded and to be present on any specific location, so If we have an opportunity to change the logging configuration file we can easily set the logging file location or name. Or take another example where we want to change the logging level or add logger for a new package we can easily do it if logging configuration file is externalized. Lets see how we can externalize logback loggin configuration file - Spring boot by default uses logback for logging and If we don't provide any configuration file It uses default configuration and prints logs in console. So if we want to make changes to the logback configuration we will have to create a logbacl configuration file. Follow below steps ...
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DSA Array | Contains duplicate

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Problem Statement You are given an array of integers, nums . Your task is to determine if the array contains any duplicate values. Return: true if any value appears more than once in the array. false if all values in the array are unique. Examples Example 1: Input: nums = [1, 2, 3, 1] Output: true   Explanation: The value 1 appears twice in the array. Example 2: Input: nums = [1, 2, 3, 4] Output: false   Explanation: All values in the array are unique. Code: class Solution { public boolean hasDuplicate(int[] nums) { int n = nums.length; Set set = new HashSet Time complexity:  O(n) Space complexity: O(n)
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