Competitive Programming

Day 35 Question: Rain water trapping in C++ Given *n* non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after raining. Input: [0,1,0,2,1,0,1,3,2,1,2,1] Output: 6 Before solving this problem, please take a look at “Container with most water (https://www.prodevelopertutorial.com/find-the-container-with-most-water-explanation-with-diagram-and-solution-in-cpp-language/)” problem. There I have explained in detail, how two pointers work. Solution: https://www.prodevelopertutorial.com/rain-water-trapping-in-c/

Group Anagrams when given an array of strings in C++ Example: Input: ["eat", "tea", "tan", "ate", "nat", "bat"], Output: [ ["ate","eat","tea"], ["nat","tan"], ["bat"] ] This problem can be solved easily using Maps. The solution involves 2 steps: 1. Sort the element and make it as the key. 2. Take the value and place it in the key. Solution: https://www.prodevelopertutorial.com/group-anagrams-in-c/

Day 33 Question: Given an n x n 2D matrix rotate it by 90 degrees (clockwise) in C++ in place You have to rotate the image in-place (https://en.wikipedia.org/wiki/In-place_algorithm), which means you have to modify the input 2D matrix directly. DO NOT allocate another 2D matrix and do the rotation. Example 1: Given input matrix = [ [1,2,3], [4,5,6], [7,8,9] ], rotate the input matrix in-place such that it becomes: [ [7,4,1], [8,5,2], [9,6,3] ] Solution: https://www.prodevelopertutorial.com/given-an-n-x-n-2d-matrix-rotate-it-by-90-degrees-clockwise-in-c-in-place/ Buy the book: https://www.instamojo.com/aj_guides/ajs-guide-to-algorithm-and-data-structure-in/

Subscribe us in Quora: https://www.quora.com/q/dailyonecodingproblem

Check if Two Trees are Mirror Structure to each other Solution: https://www.prodevelopertutorial.com/check-if-two-trees-are-mirror-structure-to-each-other/