Algorithms Coded in Java

Problem: Given an iterator of iterators, can you give me back an iterator which flattens the given iterator. Ex : Suppose you are given an iterator which has these objects - "1", "2", "3", , , then the flattened iterator returned by you should have "1", "2", "3", "4", "5", "6", "7", "8", "9". Iterators may be nested to any level. This problem can be solved by implementing a FlattenIterator which takes in the given iterator as an agrument in the constructor and delegating the hasNext() and next() calls to the given iterator using a stack. The given iterator is pushed on to the stack. Nested iterators are pushed on to the stack before traversing and once there are no more elements in the iterator, it is popped from the stack. Here is the code - import java.util.*; /** * User: blogkoder * Date: Jul 28, 2008 * Time: 9:32:39 PM */ public class FlattenIterator implement...

Problem : Given an iterator of integers, can you give me back another iterator which iterates over the given iterator of integers such that the new iterator gives only even integers. There a couple of different ways to solve this problem. * The first option is to create a new list of integers and add only the even integers from the given iterator and then return an iterator by calling list.iterator(). This has a time complexity of O (n) but also has a space complexity of O (n) in the worst case, which is not desirable. Here is the code for it - public static Iterator<Integer> giveEvenIntegersIterator(Iterator<Integer> iterator) { List<Integer> evenIntegers = new ArrayList<Integer>(); if (iterator != null) { while(iterator.hasNext()) { Integer number = iterator.next(); if (number != null && number % 2 == 0) { evenIntegers.add(number); } } } retu...