Flatten 2d Vector

Design and implement an iterator to flatten a 2d vector. It should support the following operations: next and hasNext. Example Vector2D iterator = new Vector2D([[1,2],[3],[4]]); iterator.next(); // return 1 iterator.next(); // return 2 iterator.next(); // return 3 iterator.hasNext(); // return true iterator.hasNext(); // return true iterator.next(); // return 4 iterator.hasNext(); // return false Notes Please remember to RESET your class variables declared in Vector2D, as static/class variables are persisted across multiple test cases.

by lek tin in "algorithm" access_time 2-min read

Peeking Iterator

Given an Iterator class interface with methods: next() and hasNext(), design and implement a PeekingIterator that support the peek() operation – it essentially peek() at the element that will be returned by the next call to next(). Example: Assume that the iterator is initialized to the beginning of the list: [1,2,3]. Call next() gets you 1, the first element in the list. Now you call peek() and it returns 2, the next element.

by lek tin in "algorithm" access_time 2-min read

Flatten Nested List Iterator

Given a nested list of integers, implement an iterator to flatten it. Each element is either an integer, or a list – whose elements may also be integers or other lists. Example 1 Input: [[1,1],2,[1,1]] Output: [1,1,2,1,1] Explanation: By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: `[1,1,2,1,1]`. Example 2 Input: [1,[4,[6]]] Output: [1,4,6] Explanation: By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: `[1,4,6]`.

by lek tin in "algorithm" access_time 4-min read