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What is tinyurl? tinyurl is a URL service that users enter a long URL and then the service return a shorter and unique url such as ...

Clone Graph Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors. class UndirectedGraphNode { ...

Topological Sorting Sandro is a well organised person. Every day he makes a list of things which need to be done and enumerates them from ...

Suppose you are designing a distributed caching system. Given n cache hosts, an intuitive hash function is key % n . It is simple and com...

Inorder Binary Tree Traversal with Constant Space Implementing inorder traversal with O( n ) space is pretty straight forward. Could you dev...

Count Numbers That Has A 4 In It Given a positive integer N , calculate the number of positive integers under N that has at least one dig...

Implement LRU Cache Least Recently Used (LRU) caching scheme is to discard the least recently used items first when the cache is full and a...

Implement Post-order Iterator for Binary Tree Suppose the data structure for a Tree node is as follows: public class TreeNode { int val...

Implement Pre-order Iterator for Binary Tree Suppose the data structure for a Tree node is as follows: public class TreeNode { int val; ...

Implement In-order Iterator for Binary Tree Suppose the data structure for a Tree node is as follows: public class TreeNode { int val; ...