Objective
The aim of this assignment is to understand Heap and HeapSort.
The problem specification
The problem is the same as in A2, i.e., to count the frequency of words in a text file using the sorting method. This time, the sorting method is HeapSort, and you will be required to write more code. More specifically, your tasks are:
1. (2 marks) Sort the words using HeapSort algorithm. You need to write the code for the HeapSort. Here is the template for the code, including the MergeSort so that you can have a comparison. Note that this time the template cannot run - you need to provide the missing code first for the sink procedure.
2. (2 marks) In A2, we can only print out the largest frequency. Heap is partially sorted, hence easier to get/remove the top values. Please construct a heap for frequency counts, and print out the top 20 largest counts when the data size is 1 million lines. Here is the link for the 1 million data [dblp1m]. More specifically, you need to:
- Construct a heap for frequency counts; implement the removeMax method.
- Invoke removeMax 20 times to obtain the top counts.
You can also use other programming languages of your choice. For the frequency heap, a hint is that you can write a Heap class like below:
public class HeapInt {
private int[] heap;
int n=0;
//Heap constructor
public HeapInt(int[] a){
n = a.length;
--=Z/U=UO sink(a, k, n);
heap = a;
}
public int removeMax(){
//your code goes here
}
}
