Question Link : https://leetcode.com/problems/design-add-and-search-words-data-structure/

Difficulty: Medium

Premium: False

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Design a data structure that supports adding new words and finding if a string matches any previously added string. Implement the WordDictionary class:

WordDictionary() Initializes the object. void addWord(word) Adds word to the data structure, it can …

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Question Link : https://leetcode.com/problems/add-one-row-to-tree/

Difficulty: Medium

Premium: False

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Given the root of a binary tree and two integers val and depth, add a row of nodes with value val at the given depth depth. Note that the root node is at depth 1. The adding rule …

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Question Link : https://leetcode.com/problems/find-mode-in-binary-search-tree/

Difficulty: Easy

Premium: False

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Given the root of a binary search tree (BST) with duplicates, return all the mode(s) (i.e., the most frequently occurred element) in it. If the tree has more than one mode, return them in any order …

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Question Link : https://leetcode.com/problems/clone-graph/

Difficulty: Medium

Premium: False

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Given a reference of a node in a connected undirected graph. Return a deep copy (clone) of the graph. Each node in the graph contains a value (int) and a list (List[Node]) of its neighbors.

class Node …

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Question Link : https://leetcode.com/problems/reorder-routes-to-make-all-paths-lead-to-the-city-zero/

Difficulty: Medium

Premium: False

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There are n cities numbered from 0 to n - 1 and n - 1 roads such that there is only one way to travel between two different cities (this network form a tree). Last year, The ministry of transport …

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Question Link : https://leetcode.com/problems/minimum-score-of-a-path-between-two-cities/

Difficulty: Medium

Premium: False

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You are given a positive integer n representing n cities numbered from 1 to n. You are also given a 2D array roads where roads[i] = [ai, bi, distancei] indicates that there is a bidirectional road between cities …

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Question Link : https://leetcode.com/problems/two-sum-iv-input-is-a-bst/

Difficulty: Easy

Question

Given the root of a Binary Search Tree and a target number k, return true if there exist two elements in the BST such that their sum is equal to the given target.   Example 1:

Input: root = [5,3,6 …

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