Competitive Programming

Day 24 Question: Given a linked list, swap every two adjacent nodes and return its head. Example: Given 1->2->3->4, you should return the list as 2->1->4->3. Difficulty: Medium Please write your solution in comment section of the post below: https://www.prodevelopertutorial.com/swap-nodes-in-pairs/ Programming quote for the day: “ Rules of Optimization: Rule 1: Don't do it. Rule 2 (for experts only): Don't do it yet. ” - Michael A. Jackson

Hope you have solved Day 22 question. Day 22 Question: Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses. Solution: https://www.prodevelopertutorial.com/given-n-pairs-of-parentheses-write-a-function-to-generate-all-combinations-of-well-formed-parentheses/ Please comment with your answers in the comment section of the above post.

Day 23 Question: Merge Two Sorted Lists Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists. Example: Input: 1->2->4, 1->3->4 Output: 1->1->2->3->4->4 Difficulty: Easy Programming quote for the day: “ If debugging is the process of removing software bugs, then programming must be the process of putting them in. ” - Edsger Dijkstra

Day 22 Question: Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses. For example, given n = 3, a solution set is: [ "((()))", "(()())", "(())()", "()(())", "()()()" ] Difficulty: Medium Motivational Quote for the day: Without hard work and discipline it is difficult to be a top professional.

Hope you have solved todays question. Day 21 Question: Letter Combinations of a Phone Number Solution: https://www.prodevelopertutorial.com/letter-combinations-of-a-phone-number/ Please comment with your answers in the comment section of the above post. Note: Day 20 answer shall be posted soon. Sorry for the delay.

Day 21 Question: Letter Combinations of a Phone Number Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent. A mapping of digit to letters (just like on the telephone buttons) is given below. Note that 1 does not map to any letters. Input: "23" Output: ["ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"]. Difficulty: Medium to high companies asked: flipkart Motivational Quote for the day: Perseverance is the hard work you do after you get tired of doing the hard work you already did. Note: Solution to question 20 and 21 will be provided EOD.

Day 20 Question: Remove Nth Node From End of List Given a linked list, remove the n-th node from the end of list and return its head. Example: Given linked list: 1->2->3->4->5, and n = 2. After removing the second node from the end, the linked list becomes 1->2->3->5. Note: Given n will always be valid. Follow up: Could you do this in one pass? Difficulty: Medium Motivational Quote for the day: Success isn't always about greatness. It's about consistency. Consistent hard work leads to success. Greatness will come.

Hope you have solved todays question. Day 19 Question: Given an array n integers and an integer key, are there four elements a, b, c, and d in the array such that a + b + c + d = key? Find all unique quadruplets in the array which gives the sum of key. Solution: https://www.prodevelopertutorial.com/given-an-array-n-integers-and-an-integer-key-are-there-four-elements-a-b-c-and-d-in-the-array-such-that-a-b-c/ Please comment with your answers in the comment section of the above post.

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Day 19 Question: Given an array nums of n integers and an integer target, are there elements a, b, c, and d in nums such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target. Given array nums = [1, 0, -1, 0, -2, 2], and target = 0. A solution set is: [ [-1, 0, 0, 1], [-2, -1, 1, 2], [-2, 0, 0, 2] ] Difficulty: Medium Motivational Quote for the day: Without hard work, nothing grows but weeds.

Hope you have solved todays question. Day 18 Question: Given an array of n integers and an integer “key”, find three integers in the array such that the sum is closest to key. Solution: https://www.prodevelopertutorial.com/given-an-array-of-n-integers-and-an-integer-key-find-three-integers-in-the-array-such-that-the-sum-is-closest-to-key/ Please comment with your answers in the comment section of the above post.

Day 18 Question: Given an array of n integers and an integer “key”, find three integers in the array such that the sum is closest to key. Input: [-1, 2, 1, -4] Key = 1 Output: The sum that is closest to the target is 2. (-1 + 2 + 1 = 2) This problem is also known as three sum closest You can write your answers in the commnent section of the link below: https://www.prodevelopertutorial.com/given-an-array-of-n-integers-and-an-integer-key-find-three-integers-in-the-array-such-that-the-sum-is-closest-to-key/ Difficulty: Medium Asked in Companies: Accolite Samsung CarWale Motivational Quote for the day: A dream doesn't become reality through magic; it takes sweat, determination and hard work. Note: Please spend atleast 1 hour to solve the questions. By solving 1 question a day, in a month you will be solving 30 questions and in a year 365 questions !!!

Hope you have solved todays question. Day 17 Question: Given an array, find 3 elements such that [a + b + c] = 0. Find all the 3 unique elements. Solution: https://www.prodevelopertutorial.com/given-an-array-find-3-elements-such-that-a-b-c-0-find-all-the-3-unique-elements/ Please comment with your answers in the comment section of the above post. Note: Some of you have requested me to post difficult questions. But as you can see that there are many freshers joined in this group. For them to get comfortable I am posting medium difficulty question. After some days I shall start posting more difficult questions.

Day 17 Question: Given an array, find 3 elements such that [a + b + c] = 0. Find all the 3 unique elements. Input: = [-1, 0, 1, 2, -1, -4], Output: [ [-1, 0, 1], [-1, -1, 2] ] Solve it with the time complexity O(n^2). Difficulty: Medium Companies asked: Facebook Google Motivational Quote for the day: Success is no accident. It is hard work, perseverance, learning, studying, sacrifice and most of all, love of what you are doing or learning to do. Note: All the solutions are best viewed on laptop.

Hope you have solved todays question. Question 16: Given an array of non repeating numbers and a key, find all the unique combinations in that array, where the sum of those combination is equal to the key. Solution: https://www.prodevelopertutorial.com/given-an-array-of-non-repeating-numbers-and-a-key-find-all-the-unique-combinations-in-that-array-where-the-sum-of-those-combination-is-equal-to-the-key/ Please comment with your answers in the comment section of the above post. Note: Form tomorrow, along with the question, I'll send a motivational quote. So that you feel inspired and solve the questions. Cheers :) Any feedbacks are also welcome.

Day 16 Question: Given an array of non repeating numbers and a key, find all the unique combinations in that array, where the sum of those combination is equal to the key. Input: Array = [2,3,6,7], key = 7, Output: [ [7], [2,2,3] ] Example 2: Input: candidates = [2,3,5], target = 8, A solution set is: [ [2,2,2,2], [2,3,3], [3,5] ] Try the solution with backtracking approach. Difficulty: Medium Microsoft Amazon Adobe

Hope you have solved todays question. Please comment below with your answers: Question 14: Find the Container with Most Water explanation with diagram and solution in cpp language Solution: https://www.prodevelopertutorial.com/find-the-container-with-most-water-explanation-with-diagram-and-solution-in-cpp-language/

Day 15 Question: Find the Container with Most Water Problem description: Given n non-negative integers a1, a2, …, an , where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of line i is at (i, ai) and (i, 0). Find two lines, which together with x-axis forms a container, such that the container contains the most water. [Additional explination is given in the post] The solution should be time complexity of O (n) and space complexity O( 1 ) Input: [3, 1, 2, 4, 5] Output: 12 Difficulty: Medium Company: NA Please write your answers in the comment section of the post below: https://www.prodevelopertutorial.com/find-the-container-with-most-water-explanation-with-diagram-and-solution-in-cpp-language/

Hope you have solved todays Diffcult question. Please comment below with your answers: Question 13 solution: Longest Palindromic Substring with detailed explanation and solution in C++. https://www.prodevelopertutorial.com/longest-palindromic-substring-with-detailed-explanation-and-solution-in-c/ Question 14 solution: Given an input string (s) and a pattern (p), implement regular expression matching with support for ‘.’ and ‘*’. https://www.prodevelopertutorial.com/given-an-input-string-s-and-a-pattern-p-implement-regular-expression-matching-with-support-for-and/

Todays Question 14: Given an input string (s) and a pattern (p), implement regular expression matching with support for ‘.’ and ‘*’. note: s could be empty and contains only lowercase letters a-z. p could be empty and contains only lowercase letters a-z, and characters like . or *. Example 1: Input: s = "aa" p = "a*" Output: true Explanation: '*' means zero or more of the precedeng element, 'a'. Therefore, by repeating 'a' once, it becomes Example 2: Input: s = "ab" p = ".*" Output: true Explanation: ".*" means " zero or more (*) of any character (.)". Please write the solution in below link: https://www.prodevelopertutorial.com/given-an-input-string-s-and-a-pattern-p-implement-regular-expression-matching-with-support-for-and/ Difficulty: Hard Company: Facebook, Microsoft Note: The solution for Question 13 and 14 will be provided end of the day.