Data Structure Questions and Answers – Bubble Sort

This set of Data Structure Multiple Choice Questions & Answers (MCQs) focuses on “Bubble Sort”.

1. What is an external sorting algorithm?
a) Algorithm that uses tape or disk during the sort
b) Algorithm that uses main memory during the sort
c) Algorithm that involves swapping
d) Algorithm that are considered ‘in place’
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2. What is an internal sorting algorithm?
a) Algorithm that uses tape or disk during the sort
b) Algorithm that uses main memory during the sort
c) Algorithm that involves swapping
d) Algorithm that are considered ‘in place’
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3. What is the worst case complexity of bubble sort?
a) O(nlogn)
b) O(logn)
c) O(n)
d) O(n²)
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4. Select the appropriate code that performs bubble sort.
a)

for(int j=arr.length-1; j>=0; j--)
{
	for(int k=0; k<j; k++)
	{
		if(arr[k] > arr[k+1])
		{
			int temp = arr[k];
			arr[k] = arr[k+1];
			arr[k+1] = temp;
		}
	}
}

b)

for(int j=arr.length-1; j>=0; j--)
{
	for(int k=0; k<j; k++)
	{
		if(arr[k] < arr[k+1])
		{
			int temp = arr[k];
			arr[k] = arr[k+1];
			arr[k+1] = temp;
		}
	}
}

c)

for(int j=arr.length; j>=0; j--)
{
	for(int k=0; k<j; k++)
	{
		if(arr[k] > arr[k+1])
		{
			int temp = arr[k];
			arr[k] = arr[k+1];
			arr[k+1] = temp;
		}
	}
}

d)

for(int j=arr.length; j>=0; j--)
{
	for(int k=0; k<j; k++)
	{
		if(arr[k] > arr[k+2])
		{
			int temp = arr[k];
			arr[k] = arr[k+1];
			arr[k+1] = temp;
		}
	}
}

5. What is the average case complexity of bubble sort?
a) O(nlogn)
b) O(logn)
c) O(n)
d) O(n²)
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6. Which of the following is not an advantage of optimised bubble sort over other sorting techniques in case of sorted elements?
a) It is faster
b) Consumes less memory
c) Detects whether the input is already sorted
d) Consumes less time
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7. The given array is arr = {1, 2, 4, 3}. Bubble sort is used to sort the array elements. How many iterations will be done to sort the array?
a) 4
b) 2
c) 1
d) 0
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8. How can you improve the best case efficiency in bubble sort? (The input is already sorted)
a)

        boolean swapped = false;
	for(int j=arr.length-1; j>=0 && swapped; j--)
	{
		swapped = true;
		for(int k=0; k<j; k++)
		{
			if(arr[k] > arr[k+1])
			{
				int temp = arr[k];
				arr[k] = arr[k+1];
				arr[k+1] = temp;
				swapped = false;
			}
		}
	}

b)

        boolean swapped = true;
	for(int j=arr.length-1; j>=0 && swapped; j--)
	{
		swapped = false;
		for(int k=0; k<j; k++)
		{
			if(arr[k] > arr[k+1])
			{
				int temp = arr[k];
				arr[k] = arr[k+1];
				arr[k+1] = temp;
			}
		}
	}

c)

        boolean swapped = true;
	for(int j=arr.length-1; j>=0 && swapped; j--)
	{
		swapped = false;
		for(int k=0; k<j; k++)
		{
			if(arr[k] > arr[k+1])
			{
				int temp = arr[k];
				arr[k] = arr[k+1];
				arr[k+1] = temp;
				swapped = true;
			}
		}
	}

d)

        boolean swapped = true;
	for(int j=arr.length-1; j>=0 && swapped; j--)
	{
		for(int k=0; k<j; k++)
		{
			if(arr[k] > arr[k+1])
			{
				int temp = arr[k];
				arr[k] = arr[k+1];
				arr[k+1] = temp;
				swapped = true;
			}
		}
	}

9. What is the best case efficiency of bubble sort in the improvised version?
a) O(nlogn)
b) O(logn)
c) O(n)
d) O(n²)
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10. The given array is arr = {1,2,4,3}. Bubble sort is used to sort the array elements. How many iterations will be done to sort the array with improvised version?
a) 4
b) 2
c) 1
d) 0
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