Algorithm Interview Questions

Introduction to Algorithm Interview Questions and Answers

Preparing for a job interview in Algorithm. I am sure you want to know the most common 2019 Algorithm Interview Questions and Answers that will help you crack the Algorithm Interview with ease. Below is the list of top Algorithm Interview Questions and answers at your rescue.

Below is the list of 2019 Algorithm Interview Questions and answers, which can be asked during an Interview for fresher and experience.

1.Write an algorithm to reverse a string. For example, if my string is “vahbunA” then my result will be “Anubhav”.

Answer:
Step 1: Start
Step 2: Take two variable I and j.
Step 3: j is positioned on last character (Technically we can do this by length(string)-1)
Step 4: I is positioned on first Character (we can do this by string[0])
Step 5: String[i] is interchanged String[j] Step 6: Increment I by 1
Step 7: Increment J by 1
Step 8: If ‘I’ > ‘j’ then go to step 3
Step 9: Stop

2.Write an algorithm to insert a node in linked list assuming the linked list is sorted already.

Answer:
Case 1: If linked list is empty then make the node as head and return it.
Code: New_node-> Next = head;
head = New_node
Case 2: Insert node in middle
Code: While (P!= insert_position)
{
P= p->Next;
}
Store_next= P->Next;
P->Next = New_Node;
New_Node->Next = Store_next;
Case 3: Insert a node at the end
Code: While (P->next!= null)
{
P= P->Next;
}
P->Next = New_Node;
New_Node->Next = null;

3.Write an algorithm for bubble sort.

Answer: We are going to implement the bubble sort algorithm through C language.
Step 1: Repeat Step 2 and step 3 for I = 1 to 10
Step 2: Set j = 1
Step 3: Repeat while j <= n (Where n is number of elements in the array)
{ If a[i] < a[j] Then interchange a[i] and a[j] [End of if] }
Set j = j + 1
[End of inner loop] [End of step 1 outer loop] Step 4: Exit

4.Write an algorithm for Heapsort.

Answer:
Step 1: Since the tree satisfies max-Heap property, then the largest item is stored at the root node.
Step 2: Remove the root element and put at the end of the array (nth position) put the last item of the tree (heap) at the vacant place.
Step 3: Reduce the size of the heap by 1 and heap the root element again so that we have the highest element at the root.
Step 4: The process is repeated until all the items of the list is sorted.

5.Write an algorithm for Fibonacci search.

Answer:
Step 1: A is sorted_int_array;
Step 2: take one variable c
Step 3: Fib2 = 1, Fib1 = 1 and fib = 2
Step 4: While fib < n do (where n is number of element in list)
Step 5: Assign the variable
Fib2 = Fib1
Fib1 = Fib
Fib = Fib1 + Fib2
End while
Step 6: Assign the value to temporary variable I = 0, offset = 0;
Step 7: While Fib > 1 do
I = min (offset + Fib2, n)
If c < A[i] then
Fib = Fib2
Fib1 = Fib1 – Fib2
Fib2 = Fib – Fib1
Else if c > A[i] then
Fib = Fib1;
Fib1 = Fib2;
Fib2 = Fib – Fib1;
Offset = I;
Else
Return true
End if
End while
Return false

6.Write an algorithm of push and pop operation in the stack.

Answer: For Push Operation
Procedure Add( Item, Stack, N, Top)
(Insert ‘Item’ into the ‘stack’ of maximum size ‘n’, top is the number of elements currently in ‘Stack’)
Step 1: Check Stack is overflow?
If (Top >= N)
Stack is overflow
Exit
Step 2: If the stack does not overflow, increment the loop
Top = Top + 1
Step 3: Insert the element
Stack [Top] = Item
Step 4: Exit
For POP Operation
Step 1: Check Stack is underflow means empty
If (Top <= 0)
Stack is empty
Exit
Step 2: If stack is not underflow, then deleting the element
Item = stack[top] Step 3: decrementing the top value
Top = Top – 1
Step 4: Exit

7.Write an algorithm for insert and delete operation in Queue.

Answer: For insertion operation
Procedure add(queue, F, R, N, item)
(This will insert ‘item’ in the ‘queue’ after ‘R’(rare) where ‘n’ is the size of the array.)
Step 1: Check Queue is overflow means queue is full
If (R >= N)
Queue is full
Exit
Step 2: If Queue is not overflowed, then increment the loop
R = R + 1
Step 3: Insert an element into the queue
Queue[R] = item
Step 4: Setting the ‘F’(Front) Pointer
If ( F = 0)
F = 1
Exit
For Deletion operation in Queue
Procedure delete(queue, F, R, item)
(Delete ‘item’ from the ‘stack’, ‘F’ is the Front-end pointer and ‘R’ is the rare end pointer.
Step 1: Check Queue is underflow means empty
If ( R < = 0)
Queue is empty
Exit
Step 2: Deleting an element from the queue
Item = queue [F] Step 3: Incrementing the value of F
F = F+1
Step 4: Checking the empty queue
If (F > R)
Then F = R = 0
Exit

8.Write an algorithm to find the minimum depth of a binary tree.

Answer: Let “node” be the pointer to the root node of a subtree.
Step 1: If the node is equal to Null, return 0
Step 2: If the node is a leaf node return 1.
Step 3: Recursively, find the minimum depth of left and right sub-tree, let it be left Min Depth and right min depth respectively.
Step 4: To get the minimum height of tree rooted at the node, we will take a minimum of left min depth and right min depth and 1 for the root node.
Program:
Procedure minDepth ( Node )
Step 1: if ( root = null)
Return 0
Step 2: if (root -> Left = Null and root -> right = Null )
Return 1
Step 3: if (root -> left is not null)
Return minDepth (root -> right ) + 1;
Step 4: If (root -> Right is not null )
Return minDepth ( root -> left) + 1;
Step 5: return min(minDepth (root -> left), minDepth (root -> right)) + 1

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