Every Jack has his Jill.
Every man can expect to have his partner.

Recently, I did some interesting array-related interview questions. The problem description starts like this or similar: Given an array containing numbers in the range and asks you to find duplicate/missing numbers.


A tree data structure can be defined recursively as a collection of nodes (starting at a root node), where each node is a data structure consisting of value, together with a list of references to nodes (the “children”), with the constraints that no reference is duplicated, and none points to…

Sliding window technique is useful for solving problems in array or string, especially it is considered as a technique that could reduce the time complexity from O(n²) to O(n).

There are two types of sliding window:

  1. Fixed window length k: the length of the window is fixed and it asks…

Zengrui Wang

Senior Software Engineer @Hulu

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