Test: Asymptotic Worst Case Time & Space Complexity- 3 - Computer Science Engineering (CSE) MCQ

Space complexity now is also O(n). We would need an array of size O(n). The space required for recursive calls would be O(1) as the values would be taken from stored array rather than making function calls again and again.

This is a trick question. Note that the questions asks about time complexity, not time taken by the program. for time complexity, it doesn't matter how we store array elements, we always need to access same number of elements of M1 and M2 to multiply the matrices. It is always constant or O(1) time to do element access in arrays, the constants may differ for different schemes, but not the time complexity.

Please note that inside the else condition, f() is called first, then counter is set to 0. Consider the following cases:

(n + k)^m and Θ(n^m) are asymptotically same as theta notation can always be written by taking the leading order term in a polynomial expression. 2^{n + 1} and O(2ⁿ) are also asymptotically same as 2^{n + 1} can be written as 2 * 2ⁿ and constant multiplication/addition doesn't matter in theta notation. 2^{2n + 1} and O(2ⁿ) are not same as constant is in power. See Asymptotic Notations for more details.

Insertion sort runs in Θ(n + f(n)) time, where f(n) denotes the number of inversion initially present in the array being sorted.

Randomized quicksort has expected time complexity as O(nLogn), but worst case time complexity remains same. In worst case the randomized function can pick the index of corner element every time.

In worst case, the chosen pivot is always placed at a corner position and recursive call is made for following.
a) for subarray on left of pivot which is of size n-1 in worst case.
b) for subarray on right of pivot which is of size 0 in worst case.

T(n) = n(logn + loglogn) T(n) = n(logn) dominant But please note here we are return q which lies in loglogn so ans should be T(n) = nloglogn Refer this for details.

We only need to consider any 3 elements and compare them. So the number of comparisons is constants, that makes time complexity as Θ(1) The catch here is, we need to return any element that is neither maximum not minimum. Let us take an array {10, 20, 15, 7, 90}. Output can be 10 or 15 or 20 Pick any three elements from given liar. Let the three elements be 10, 20 and 7. Using 3 comparisons, we can find that the middle element is 10.

X = Sum of the cubes of {1, 2, 3, .. n| X = n² (n+1)² / 4

• Bellman-Ford algorithm: Time complexity: O(VE)
• Kruskal’s algorithm:Time Complexity: O(ElogE) or O(ElogV). Sorting of edges takes O(ELogE) time. After sorting, we iterate through all edges and apply find-union algorithm. The find and union operations can take atmost O(LogV) time. So overall complexity is O(ELogE + ELogV) time. The value of E can be atmost V^2, so O(LogV) are O(LogE) same. Therefore, overall time complexity is O(ElogE) or O(ElogV)
• Floyd-Warshall algorithm: Time Complexity: O(V^3)
• Topological sorting: Time Complexity: The above algorithm is simply DFS with an extra stack. So time complexity is same as DFS which is O(V+E).

n^(log_ba) = n which is = n^(1-.5) = O(sqrt n) then by applying case 1 of master method we get T(n) = Θ(n)

• Insertion Sort takes Θ(n²) in worst case as we need to run two loops. The outer loop is needed to one by one pick an element to be inserted at right position. Inner loop is used for two things, to find position of the element to be inserted and moving all sorted greater elements one position ahead. Therefore the worst case recursive formula is T(n) = T(n-1) + Θ(n).
• Merge Sort takes Θ(n Log n) time in all cases. We always divide array in two halves, sort the two halves and merge them. The recursive formula is T(n) = 2T(n/2) + Θ(n).
• QuickSort takes Θ(n²) in worst case. In QuickSort, we take an element as pivot and partition the array around it. In worst case, the picked element is always a corner element and recursive formula becomes T(n) = T(n-1) + Θ(n). An example scenario when worst case happens is, arrays is sorted and our code always picks a corner element as pivot.

I. Given an array in ascending order, Recurrence relation for total number of comparisons for quicksort will be T(n) = T(n-1)+O(n) //partition algo will take O(n) comparisons in any case. = O(n^2)
II. Bubble Sort runs in Θ(n^2) time If an array is in ascending order, we could make a small modification in Bubble Sort Inner for loop which is responsible for bubbling the kth largest element to the end in kth iteration. Whenever there is no swap after the completion of inner for loop of bubble sort in any iteration, we can declare that array is sorted in case of Bubble Sort taking O(n) time in Best Case.
III. Merge Sort runs in Θ(n) time Merge Sort relies on Divide and Conquer paradigm to sort an array and there is no such worst or best case input for merge sort. For any sequence, Time complexity will be given by following recurrence relation, T(n) = 2T(n/2) + Θ(n) // In-Place Merge algorithm will take Θ(n) due to copying an entire array. = Θ(nlogn)
IV. Insertion sort runs in Θ(n) time Whenever a new element which will be greater than all the elements of the intermediate sorted sub-array (because given array is sorted) is added, there won't be any swap but a single comparison. In n-1 passes we will be having 0 swaps and n-1 comparisons. Total time complexity = O(n) // N-1 Comparisons

//// For an array already sorted in ascending order, Quicksort has a complexity Θ(n²) [Worst Case] Bubblesort has a complexity Θ(n) [Best Case] Mergesort has a complexity Θ(n log n) [Any Case] Insertsort has a complexity Θ(n) [Best Case] 

A problem in NP becomes NPC if all NP problems can be reduced to it in polynomial time. This is same as reducing any of the NPC problem to it. 3-SAT being an NPC problem, reducing it to a NP problem would mean that NP problem is NPC.

Background Required -  Generating Prefix codes using Huffman Coding. First we apply greedy algorithm on the frequencies of the characters to generate the binary tree as shown in the Figure given below. Assigning 0 to the left edge and 1 to the right edge, prefix codes for the characters are as below.

a - 1111110
b - 1111111
c - 111110
d - 11110
e - 1110
f - 110
g - 10
h - 0
Given String can be decomposed as 110 11110 0 1110 10 fdheg

A set of vertices is called independent set such that no two vertices in the set are adjacent. A maximal independent set (MIS) is an independent set which is not subset of any other independent set. The question is about smallest MIS. We can see in below diagram, the three highlighted vertices (2nd, 5th and 8th) form a maximal independent set (not subset of any other MIS) and smallest MIS.

0----0----0----0----0----0----0----0----0