Construct Binary Tree from Given Inorder and Preorder Traversals

In this problem, we have inorder and preorder of the binary tree. We need to construct a binary tree from the given Inorder and Preorder traversals. Example Input: Inorder= [D, B, E, A, F, C] Preorder= [A, B, D, E, C, F] Output: Pre-order traversal of the tree formed by …

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K-th Distinct Element in an Array

You are given an integer array A, print k-th distinct element in an array. The given array may contain duplicates and the output should print k-th distinct element among all unique elements in an array. If k is more than a number of distinct elements, then report it. Example Input: …

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Insert Delete GetRandom

In Insert Delete GetRandom problem we need to design a data structure that supports all following operations in average O(1) time. insert(val): Inserts an item val to the set if not already present. remove(val): Removes an item val from the set if present. getRandom: Returns a random element from the current set …

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Merge Overlapping Intervals

In merge overlapping intervals problem we have given a collection of intervals, merge and return all overlapping intervals. Example Input : [[2, 3], [3, 4], [5, 7]] Output: [[2, 4], [5, 7]] Explanation: We can merge [2, 3] and [3, 4] together to form [2, 4] Approach for finding Merge …

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Decode Ways

In Decode Ways problem we have given a non-empty string containing only digits, determine the total number of ways to decode it using the following mapping: ‘A’ -> 1 ‘B’ -> 2 … ‘Z’ -> 26 Example S = “123” Number of ways to decode this string is 3 If we …

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Check if Two Expressions With Brackets are Same

Given two strings s1 and s2 representing expressions containing addition operator, subtraction operator, lowercase alphabets, and parenthesis. Check if two expressions with brackets are the same. Example Input  s1 = “-(a+b+c)” s2 = “-a-b-c” Output  Yes Input  s1 = “a-b-(c-d)” s2 = “a-b-c-d” Output No Algorithm to Check if Two …

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