Counting Loops and Comparisons

Question

I need to count the number of loops and comparisons which occur over four different sorting methods. I am using the Selection, Bubble, Insertion, and Quick sort methods. Ideally, I would just place a int such as loopCounter and ++ it every time it loops/compares. Although, being quite new to all of this, I am having trouble distinguishing when I need to include such counters. As you will be able to see in the following code, I attempted to create multiple counters. Although, I think only the selection counters are correct so far.

Additionally, I am required to count the number of times that a value is shifted. In other words, how many times integers are swapped.

Any help with this would be extremely appreciated!

Thanks

    ArrayList<Integer> list = new ArrayList<Integer>();

    //Counters for Selection Sort
    int loopCounter = 0;
    int compCounter = 0;
    //Counters for Bubble Sort
    int loopCounter2 = 0;
    int compCounter2 = 0;
    //Counters for Insertion Sort
    int loopCounter3 = 0;
    int compCounter3 = 0;
    //Counters for Quick Sort
    int loopCounter4 = 0;
    int compCounter4 = 0;

public void selectionSort(Integer[] a) {

    for(int i = 0; i < a.length; i++) {
        int smallestValue = a[i];
        int smallestIndex = i;
        if(ascButton.isSelected()){
            for(int j = i+1; j < a.length; j++) {
                if (smallestValue > a[j]) {
                    smallestValue = a[j];
                    smallestIndex = j;
                    loopCounter++;
                    compCounter++;
                }
            }
        a[smallestIndex] = a[i];
        a[i] = smallestValue;
        } else if(desButton.isSelected()){
            for(int j = i+1; j < a.length; j++) {
                if (smallestValue < a[j]) {
                    smallestValue = a[j];
                    smallestIndex = j;
                    loopCounter++;
                    compCounter++;
                }
        }
        a[smallestIndex] = a[i];
        a[i] = smallestValue;
        }
    }
}

public void bubbleSort(Integer[] a) {

    int temp;

    for (int i = a.length - 1; i > 0; i--) {
        if(ascButton.isSelected()) {
            for(int j = 0; j < i; j++) {
                loopCounter2++;
                compCounter2++;
                if(a[j] > a[j + 1]) {
                    temp = a[j];
                    a[j] = a[j + 1];
                    a[j + 1] = temp;
                }
            }
            } else if(desButton.isSelected()) {
                for(int j = 0; j < i; j++) {
                    loopCounter2++;
                    compCounter2++;
                    if(a[j] < a[j + 1]) {
                        temp = a[j];
                        a[j] = a[j + 1];
                        a[j + 1] = temp; 
                    }
                }
            }

    }
}

public void insertionSort(Integer[] a) {
    for(int i = 1; i < a.length; i++) {
        loopCounter3++;
        compCounter3++;
        int temp = a[i];
        int j = i - 1;

        if(ascButton.isSelected()) {
            while(j >= 0 && a[j] > temp) {
            a[j + 1] = a[j];
            j--;
        }
        a[j + 1] = temp;
        } else if(desButton.isSelected()) {
            while(j >= 0 && a[j] < temp) {
            a[j + 1] = a[j];
            j--;
        }
        a[j + 1] = temp;
        }

    }
}

public void quickSort(Integer[] a, int left, int right) {
    int i = left;
    int j = right;
    int temp;
    int pivot = a[(left + right)/2];
    while(i <= j) {
    if(ascButton.isSelected()) {
        while(a[i] < pivot)
            i++;
        while(a[j] > pivot)
            j--;
    } else if(desButton.isSelected()) {
        while(a[i] > pivot)
            i++;
        while(a[j] < pivot)
            j--;
    }
        if(i <= j) {
            temp = a[i];
            a[i] = a[j];
            a[j] = temp;
            i++;
            j--;
        }
    }
    if(left < j) {
        quickSort(a,left,j);
    }  
    if(i < right) {
        quickSort(a, i, right);
    }            
}

Answer 1

As @Andreas suggested, your loop and comparison counters are in place correctly. As far as the swap counter is concerned, think of it this way - you cannot swap without a temp variable. As a result, whenever a temp variable is involved you want to increase your swap counter. As an example, for your quicksort, it would look like this:

public void quickSort(Integer[] a, int left, int right) {
    int i = left;
    int j = right;
    int temp;
    int pivot = a[(left + right)/2];
    while(i <= j) {
    if(ascButton.isSelected()) {
        while(a[i] < pivot)
            i++;
        while(a[j] > pivot)
            j--;
    } else if(desButton.isSelected()) {
        while(a[i] > pivot)
            i++;
        while(a[j] < pivot)
            j--;
    }
        if(i <= j) {
            temp = a[i];
            a[i] = a[j];
            a[j] = temp;
            i++;
            j--;
            swapCounterForQuickSort++;
        }
    }
    if(left < j) {
        quickSort(a,left,j);
    }  
    if(i < right) {
        quickSort(a, i, right);
    }            
}

Follow the same logic for your other sorts.

Also, some general suggestions:

• Always name variables so that they tell you what they are used for. Rather than loopCounter1 try using loopCounterForSelectionSort and so on. Don't be afraid of long variable names. Information is power!
• Make your functions as short and reusable as possible. For example, you swap integers a lot in your code. Maybe you can just copy the swap code and paste it into a swapIntegers() function. Then everytime you just call this function when you want to swap! Also, notice how this makes your swap counter question easier to answer since you can put a counter in the swap method to do the counting for you. (Although be aware since multiple methods will call the swap counter so you may want to pass it as an argument etc.)

Answer 2

With counters, you simply want to "count" when you want to program to count something. So if you don't understand your own code, then it will be difficult to know when you want to "count" something. I suggest you figure out when a swap is happening, when that is happening in your code, that is when you want to do some sort of:

    swapCount++;//Each time a swap happens increment by 1
    iterationCount++//A full pass has happened increment by 1

Note: above just because a full pass has happened in many sort, which you probably know, does not mean it is sorted, it is just saying it has done 1 pass.

I'm not sure if this theory will help you any. Give me some feedback on what your still having trouble with and I'll see if I can change my answer to better reflect what your looking for.