Phone interview question # 1: Given an array (for example, [ 1, 0, 2, 0, 0, 3, 4 ]), implement methods that 1. returns the number of non-zero elements (4) 2. moves the non-zero elements to the beginning of the array (the rest of the elements don't matter) -> both [ 1, 2, 3, 4, 0, 0, 0] and [ 4, 1, 3, 2, X, Y, Z ] are valid
Given an array, without using extra space, move all zeros to the end and no-zeros to the beginning. The function should return the number of non-zeros.
Verify that a binary search tree is indeed a binary search tree.
- Given an array, remove the duplicates and return a unique array keeping the first occurrence of the duplicates and the order. [@2, @1, @3, @1, @2] --> [@2, @1, @3] - how would you implement call for canceling queued blocks with dispatch_after?
Given a list of number 8 4 3 0 6 4 0, move all 0's to start of the list. use minimum sorting rounds
How to detect a common superview.
given an array of words, how to eliminate the duplicates? You have a simple tree structure Ⓐ and its clone ⓐ. Each node in the tree has a pointer to it's parent as well as an array of its children. Given an original tree's node Ⓑ and cloned tree ⓐ, implement a method that returns ⓑ (the clone of Ⓑ). (Imagine finding the matching UIButton/UISlider/UIView in a separate cloned view controller.) Original Ⓐ ┏━┻━━┓ ◯ ◯ ┏┻┓ ┏━╋━┓ ◯ ◯ ◯ ◯ ◯ ┏┻┓ ┃ ◯ Ⓑ ◯ Clone ⓐ ┏━┻━━┓ ◯ ◯ ┏┻┓ ┏━╋━┓ ◯ ◯ ◯ ◯ ◯ ┏┻┓ ┃ ◯ ⓑ ◯
Given nested arrays, write an enumerator class such that next() returns the elements in sequential order, e.g.: [1,[4,3],6,[5,[1,0]]] -> 1, 4, 3, 6, 5, 1, 0 also implement allObjects for this class
Take in an Int array and move all the zeroes to the end in place. It doesn’t matter how the non-zero numbers are ordered. Preferably as efficient and as space efficient as possible. Example: Input : [ 3, 0, 2, 0, 0, 4, 1, 0 ] Accepted Output: [ 4, 2, 3, 1, 0, 0, 0, 0 ]
If you have a program that runs slow, how will you improve it to run faster?
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