sorts.java

//----------------------------------------------------------------------------

//Sorts.java by Dale/Joyce/Weems Chapter 10

//

//Test harness used to run sorting algorithms.

//----------------------------------------------------------------------------

import java.util.*;

import java.text.DecimalFormat;

public class Sorts

{

static final int SIZE = 50; // size of array to be sorted

static int[] values = new int[SIZE]; // values to be sorted

static int swap = 0;

static int comparison = 0;

static void initValues()

// Initializes the values array with random integers from 0 to 99.

{

Random rand = new Random();

for (int index = 0; index

values[index] = Math.abs(rand.nextInt()) % 100;

}

static public boolean isSorted()

// Returns true if the array values are sorted and false otherwise.

{

boolean sorted = true;

for (int index = 0; index

if (values[index] > values[index + 1])

sorted = false;

return sorted;

}

static public void swap(int index1, int index2)

// Precondition: index1 and index2 are >= 0 and

//

// Swaps the integers at locations index1 and index2 of the values array.

{

swap++;

int temp = values[index1];

values[index1] = values[index2];

values[index2] = temp;

}

static public void printValues()

// Prints all the values integers.

{

int value;

DecimalFormat fmt = new DecimalFormat("00");

System.out.println("The values array is:");

for (int index = 0; index

{

value = values[index];

if (((index + 1) % 10) == 0)

System.out.println(fmt.format(value));

else

System.out.print(fmt.format(value) + " ");

}

System.out.println();

}

/////////////////////////////////////////////////////////////////

//

// Selection Sort

static int minIndex(int startIndex, int endIndex)

// Returns the index of the smallest value in

// values[startIndex]..values[endIndex].

{

int indexOfMin = startIndex;

for (int index = startIndex + 1; index

comparison++;

if (values[index]

indexOfMin = index;

}

return indexOfMin;

}

static void selectionSort()

// Sorts the values array using the selection sort algorithm.

{

int endIndex = SIZE - 1;

for (int current = 0; current

swap(current, minIndex(current, endIndex));

}

/////////////////////////////////////////////////////////////////

//

// Bubble Sort

static void bubbleUp(int startIndex, int endIndex)

// Switches adjacent pairs that are out of order

// between values[startIndex]..values[endIndex]

// beginning at values[endIndex].

{

for (int index = endIndex; index > startIndex; index--){

comparison++;

if (values[index]

swap(index, index - 1);

}

}

static void bubbleSort()

// Sorts the values array using the bubble sort algorithm.

{

int current = 0;

while (current

{

bubbleUp(current, SIZE - 1);

current++;

}

}

/////////////////////////////////////////////////////////////////

//

// Short Bubble Sort

static boolean bubbleUp2(int startIndex, int endIndex)

// Switches adjacent pairs that are out of order

// between values[startIndex]..values[endIndex]

// beginning at values[endIndex].

//

// Returns false if a swap was made; otherwise, returns true.

{

boolean sorted = true;

for (int index = endIndex; index > startIndex; index--){

comparison++;

if (values[index]

{

swap(index, index - 1);

sorted = false;

}

}

return sorted;

}

static void shortBubble()

// Sorts the values array using the bubble sort algorithm.

// The process stops as soon as values is sorted.

{

int current = 0;

boolean sorted = false;

while ((current

{

sorted = bubbleUp2(current, SIZE - 1);

current++;

}

}

/////////////////////////////////////////////////////////////////

//

// Insertion Sort

static void insertItem(int startIndex, int endIndex)

// Upon completion, values[0]..values[endIndex] are sorted.

{

boolean finished = false;

int current = endIndex;

boolean moreToSearch = true;

while (moreToSearch && !finished)

{

comparison++;

if (values[current]

{

swap(current, current - 1);

current--;

moreToSearch = (current != startIndex);

}

else

finished = true;

}

}

static void insertionSort()

// Sorts the values array using the insertion sort algorithm.

{

for (int count = 1; count

insertItem(0, count);

}

/////////////////////////////////////////////////////////////////

//

// Merge Sort

static void merge (int leftFirst, int leftLast, int rightFirst, int rightLast)

// Preconditions: values[leftFirst]..values[leftLast] are sorted.

// values[rightFirst]..values[rightLast] are sorted.

//

// Sorts values[leftFirst]..values[rightLast] by merging the two subarrays.

{

int[] tempArray = new int [SIZE];

int index = leftFirst;

int saveFirst = leftFirst; // to remember where to copy back

while ((leftFirst

{

comparison++;

if (values[leftFirst]

{

tempArray[index] = values[leftFirst];

leftFirst++;

}

else

{

tempArray[index] = values[rightFirst];

rightFirst++;

}

index++;

}

while (leftFirst

// Copy remaining items from left half.

{

tempArray[index] = values[leftFirst];

leftFirst++;

index++;

}

while (rightFirst

// Copy remaining items from right half.

{

tempArray[index] = values[rightFirst];

rightFirst++;

index++;

}

for (index = saveFirst; index

values[index] = tempArray[index];

}

static void mergeSort(int first, int last)

// Sorts the values array using the merge sort algorithm.

{

comparison++;

if (first

{

int middle = (first + last) / 2;

mergeSort(first, middle);

mergeSort(middle + 1, last);

merge(first, middle, middle + 1, last);

}

}

/////////////////////////////////////////////////////////////////

//

// Quick Sort

static int split(int first, int last)

{

int splitVal = values[first];

int saveF = first;

boolean onCorrectSide;

first++;

do

{

onCorrectSide = true;

while (onCorrectSide){ // move first toward last

comparison++;

if (values[first] > splitVal)

onCorrectSide = false;

else

{

first++;

onCorrectSide = (first

}

}

onCorrectSide = (first

while (onCorrectSide) { // move last toward first

comparison++;

if (values[last]

onCorrectSide = false;

else

{

last--;

onCorrectSide = (first

}

}

comparison++;

if (first

{

swap(first, last);

first++;

last--;

}

} while (first

swap(saveF, last);

return last;

}

static void quickSort(int first, int last)

{

comparison++;

if (first

{

int splitPoint;

splitPoint = split(first, last);

// values[first]..values[splitPoint - 1]

// values[splitPoint] = splitVal

// values[splitPoint+1]..values[last] > splitVal

quickSort(first, splitPoint - 1);

quickSort(splitPoint + 1, last);

}

}

/////////////////////////////////////////////////////////////////

//

// Heap Sort

static int newHole(int hole, int lastIndex, int item)

// If either child of hole is larger than item this returns the index

// of the larger child; otherwise it returns the index of hole.

{

int left = (hole * 2) + 1;

int right = (hole * 2) + 2;

comparison++;

if (left > lastIndex)

// hole has no children

return hole;

else{

comparison++;

if (left == lastIndex){

comparison++;

// hole has left child only

if (item

// item

return left;

else

// item >= left child

return hole;

}

else{

comparison++;

// hole has two children

if (values[left]

comparison++;

// left child

if (values[right]

// right child

return hole;

else

// item

return right;

}

else{

comparison++;

// left child >= right child

if (values[left]

// left child

return hole;

else

// item

return left;

}

}

}

}

static void reheapDown(int item, int root, int lastIndex)

// Precondition: Current root position is "empty".

//

// Inserts item into the tree and ensures shape and order properties.

{

int hole = root; // current index of hole

int newhole; // index where hole should move to

newhole = newHole(hole, lastIndex, item); // find next hole

while (newhole != hole)

{

values[hole] = values[newhole]; // move value up

hole = newhole; // move hole down

newhole = newHole(hole, lastIndex, item); // find next hole

}

values[hole] = item; // fill in the final hole

}

static void heapSort()

// Sorts the values array using the heap sort algorithm.

{

int index;

// Convert the array of values into a heap.

for (index = SIZE/2 - 1; index >= 0; index--)

reheapDown(values[index], index, SIZE - 1);

// Sort the array.

for (index = SIZE - 1; index >=1; index--)

{

swap(0, index);

reheapDown(values[0], 0, index - 1);

}

}

/////////////////////////////////////////////////////////////////

//

// Main

public static void main(String[] args)

{

initValues();

printValues();

System.out.println("values is sorted: " + isSorted());

System.out.println();

// make call to sorting method here (just remove //)

Sorts.comparison = 0;

Sorts.swap = 0;

selectionSort();

System.out.println("Number of comparisons: "+Sorts.comparison);

System.out.println("Number of swaps: "+Sorts.swap);

// reseting to zero

Sorts.comparison = 0;

Sorts.swap = 0;

// bubbleSort();

// shortBubble();

// insertionSort();

// mergeSort(0, SIZE - 1);

// quickSort(0, SIZE - 1);

// heapSort();

printValues();

System.out.println("values is sorted: " + isSorted());

System.out.println();

}

}

10. In Exercise 1 you were asked to modify the sorts program so that it would out- put the number of swaps used by a sorting method. It is a little more difficult to have the program also output the number of comparisons (compares) needed. You must include one or more statements to increment your counter within the sorting methods themselves. For each of the listed methods, make and test the changes needed, and list both the number of swaps and the number of compares needed by the Sorts program to sort an array of 50 random integers. a. selection Sort Swaps compares: b. bubbles ort Swaps compares c. short Bubble Swaps compares: d. insertions Swaps compares sort