Write a function to determine if a bin tree is a valid BST. I wrote a fully working solution in 3-5 minutes. It was also the most optimal but maybe because she needed to kill time, she asked me to rewrite it in what she thought was optimal (her reasoning didn't make much sense). Then she asked me for time and space requirements of the solutions. I said O(n) for both which is correct but she insisted that the space requirement was O(logn) which is wrong.
Print a binary tree level by level
Write a function in Java that will take a sorted array of ints, possibly with duplicates, and compact the array removing all the duplicate numbers. That is, if the contains the numbers - 1, 3, 7, 7, 8, 9, 9, 9, 10, then when the function returns, the contents should be - 1, 3, 7, 8, 9, 10. Be sure your answer is as efficient as possible. Describe the efficiency of your algorithm using big O notation.
Given a set of points (x,y) and an integer "n", return n number of points which are close to the origin
Given a number n, give me a function that returns the nth fibonacci number. Running time, space complexity, iterative vs. recursive.
Find the length of the longest chain of consecutive integers in an unsorted set in linear time.
Given a collection of words, return a collection of anagrams found in the given collection
Given a binary tree, which is not necessarily balanced, print the nodes in the tree in a level-wise manner. Also, nodes on the same level should be printed on a single line. A modification of the question was added later in which I cannot really add a "level" variable in the structure of the node in the tree.
Given a log of users visit to a site for a day, how would you find returning users given the log visit for another day
Write a program to find the square root of a double.
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