More arraylist practice problems

MoreArrayList.java

import java.util.*;

public class MoreArrayList
{
  // Think!
  //
  // What are the repeatable units of work?
  // This is what goes in the for loop.
  //
  // If you see the keyword "every" or "for every X do Y"
  // there's probably a loop involved.
  //
  // What are the subproblems? If X is hard to do,
  // would it be easier if you already have Y? If yes, then
  // solving Y first is a subproblem.

  public static void normalize(ArrayList<Double> input) {
    // Normalize the input:
    // This means scale all the values in the input
    // so that they fit from 0 to 1 (this means dividing
    // each element by the max element).
  }

  public static void shuffle(ArrayList<Integer> numbers) {
    // Rearrange the items in numbers so that they are in a
    // random order.
  }

  public static void removeDuplicates(ArrayList<String> words) {
    // Remove all duplicate Strings that appear in |words|.
    // This means that if a word shows up twice, remove
    // the second appearance of that word from |words|. If it
    // shows up more than twice, remove ALL duplicate appearances
    // of that word from |words|.
    //
    // Be careful of going out of bounds!
  }

  public static int findLongestIncreasingSequence(ArrayList<Integer> numbers) {
    // Okay, so first think: How can you break this problem
    // down into easier sub-problems? (Hint: What if you had an
    // ArrayList of ArrayLists....woahhh, so meta).
    return 0;
  }

  // Next question is very very similar to what you did last week!
  private static class Item {
    int value;
    int count;
  }

  public static ArrayList<Item> buildHistogram(ArrayList<Integer> numbers) {
    // Build a histogram of how many times a number appears in
    // numbers.
    //
    // For each unique number that appears in numbers,
    // create an "Item" object where |value| is that number and
    // |count| is the number of times that number is scene in numbers.
    return null;
  }

  public static ArrayList<Integer> simpleSort(ArrayList<Integer> input)
  {
    // Returns a sorted version of the input.
    // Use the following strategy:
    // Take each int in input one at a time and
    // insert them into a new ArrayList that is
    // originally empty. Every time you add a new
    // int, you add it into the right place so that
    // the new ArrayList remains sorted.
    return null;
  }

  // Challenge question:
  public static void insertionSort(ArrayList<Integer> input)
  {
    // A fancier version of simple sort. Use a SINGLE ArrayList.
    // Destructively modify the ArrayList that was given to you
    // instead of creating a new sorted ArrayList.
    //
    // The solution to this problem is known as insertion sort.
    // (We'll revisit this later in the searching and sorting
    // chapter).
  }
}