# Pancake Sort – Data Structure Questions and Answers

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

1. How many flips does the simplest of pancake sorting techniques require?
A) 3n−3 flips
B) 2n-4 flips
C) 2n-3 flips
D) 3n-2 flips

Explanation: It has been determined that the minimum number of flips needed to sort any stack of n pancakes is between 1.087n and 1.636n. Taking the average of that 1.36n and extracting it for n>1 values We’ve got 1.36, 2.72, 4.08, and so on. This is better matched with 2n-3, which is equivalent to 1, 3, 5, 7, 9, and so on. Iteratively using the next largest element in its correct position using two flips yields an upper bound of 2n-3.

2. Pancake Sorting appears in which of the following?
A) Frequency Scaling
B) Storage Virtualization
C) Parallel Processing
D) Neural Networking

Explanation: Pancake Sorting has applications in educational settings as well as parallel processing networks, as it provides optimal network routing algorithms.

3. In addition to the pancake sorting problem, there is the case of the burnt pancake problem in which we are dealing with pancakes (discs) that are burnt on one side only. In this case it is taken that the burnt side must always end up _______
A) Faced down
B) Faced up
C) It doesn’t matter
D) Both sides are burnt

Explanation: Burnt pancakes are a variation of this pancake. Each pancake in this recipe has a burnt side, and all pancakes must end up with the burnt side on the bottom. It’s a tougher version of the standard pancake issue.

4. In a computational complexity theory, a problem with decision making is said to be NP-complete when it is both in NP and NP-hard. What does NP mean?
A) Non Polynomial time
B) Non-deterministic Probabilistic
C) Non-deterministic Polynomial time
D) Non Probabilistic time

Explanation: While any given solution to an NP-complete problem can be verified in polynomial time, there is no way to find a solution quickly in the first place. Since there is no known quick solution to NP-complete problems, they are referred to as non-deterministic polynomial time problems.

5. When we realize a specific implementation of a pancake algorithm, every move when we find the greatest of the sized array and flipping can be modeled through __________
A) Combinations
B) Exponential functions
C) Logarithmic functions
D) Permutations

Explanation: When flipping an array or stack, the order of the list must be preserved at all costs so that the sorting does not become invalid. As a result, we use permutations to ensure that order is important.

6. The Pancake Problems (1975, 1979, 1973) did NOT involve which of the following people?
A) Bill Gates
B) Jacob Goodman
C) Christos Papadimitriou
D) John Goodman

Explanation: (Jacob Goodman – 1975) What is the maximum number of flips needed to sort a permutation of [n] into ascending order?
(Bill Gates and Christos Papadimitriou – 1979) What is the maximum number of flips needed to sort a signed permutation of [n] into ascending order with all positive signs?

7. There is a one line error in the following routine. Find that line.

```		1.	int Max(int a[], int n)
2.	{
3.		  int mi, i;
4.		  for (mi = 0, i = 0; i < n; i++)
5.		  if (a[i] > a[mi])
6.		  mi = i;
7.		  return mi;
8.	}```

A) Line 2
B) Line 4
C) Line 6
D) Line 5

Explanation: The for loop declaration’s increment condition is wrong. Instead of i++, we can use I

8. What is the time complexity for a given pancake sort given it undergoes “n” flip operations?
A) O(n)
B) O(n2)
C) O(n3)
D) O(2n)

Explanation: Most sorting algorithms aim to sort with the fewest possible comparisons, but in pancake sort, we try to sort with the fewest possible reversals. The overall time complexity of a pancake sort is O(n) since the total number of flip operations is O(n) (n2).

9. Which operation is most essential to the process of pancake sort?
A) Flip the given data
B) Find the largest of given data
C) Finding the least of given data
D) Inserting something into the given data

Explanation: When we use pancake sort, we first sort the array to find the largest value, then flip the array to transfer that value to the bottom of the stack. After that, the size of the array we’re working with is reduced, and the process continues. The most significant feature in the pancake sorting technique is the flip process.

10. There is one small error in the following flip routine. Find out which line it is on.

```	1	void flip(int arr[], int i)
2	{
3	      int t, init = 0;
4	      while (init < i)
5	      {
6		    t = arr[init];
7		    arr[i] = arr[init] ;
8		    arr[i] = t;
9		    init++;
10		    i--;
11	      }
12	}```

A) Line 3
B) Line 5
C) Line 7
D) Line 9

Explanation: After initialising the arr array, we should set arr[init]=arr[i] for each while loop iteration of increasing init. This ensures that the modifications will be made in order to flip the array’s order, which was supposed to be reversed. Line 7 has been written backwards, which is inaccurate.

When a spatula can be inserted at any point in the stack and used to turn all pancakes above it, pancake sorting is a mathematical problem of sorting a disordered stack of pancakes in order of height. The minimum number of pancake flips needed for a given number of pancakes is known as the pancake number. The problem was first discussed in this form by American geometer Jacob E. Goodman. Burnt pancakes are a variation of the issue in which each pancake has a burnt side and all pancakes must end up with the burnt side on the bottom. Any sorting method necessitates the comparison of two items.