The document contains 6 technical interview questions asked during an August Infotech technical round. The questions cover algorithms for reversing a string using a stack, sorting a list using merge sort, deleting nodes in a linked list, finding the pair of elements with the closest sum to zero in an array, writing a SQL query to filter customers by city or grade, and writing a SQL query to count customers with a grade. Code solutions are provided for each algorithm question.

1. Aastha Shah_Ganpat University
August_Infotech Technical Round Questions.
Que1. Write a program or algorithm to Reverse a String using the Stack method. [5
marks]
input: Hello World!
output: !dlroW olleH
Code:
def createStack():
stack=[]
return stack
def size(stack):
return len(stack)
def empty(stack):
if size(stack) == 0:
return true
def push(stack, item):
stack.append(item)
def pop(stack):
if empty(stack):
return

2. Aastha Shah_Ganpat University
return stack.pop()
def reverse(string):
n = len(string)
stack = createStack()
for i in range(0,n,1):
push(stack, string[i])
string = ""
for i in range(0,n,1):
string += pop(stack)
return string
string = "Hello World"
string = reverse(string)
print("Reversed string is" + string)

3. Aastha Shah_Ganpat University

4. Aastha Shah_Ganpat University
Que 2. Write a program or algorithm to sort list using the merge sort method. [10
marks]
input: 6 5 4 7 1
output after merge sort: 1 4 5 6 7
Code:
def mergeSort(arr):
if len(arr) > 1:
mid = len(arr) // 2
L = arr[:mid]
R = arr[mid:]
mergeSort(L)
mergeSort(R)
i=j=k=0
while i<len(L) and j<len(R):
if L[i] <= R[j]:
arr[k] = L[i]
i+=1
else:
arr[k] = arr[R]
j+=1
k+=1

5. Aastha Shah_Ganpat University
while i<len(L):
arr[k] = L[i]
i+=1
k+=1
while i<len(R):
arr[k] = R[j]
j+=1
k+=1
def printList(arr):
for i in range(len(arr)):
print(arr[i], end=" ")
print()
if _name_ == '__main__':
arr = [6,5,4,7,1]
print("Given arry is", end="n")
printList(arr)
mergeSort(arr)
print("Sorted array is:", end="n")
printList(arr)

6. Aastha Shah_Ganpat University
Que 3. Write a program or algorithm to Delete N nodes after M nodes of a linked
list. [10 marks]
Example-1
input: 1 → 2 → 3 → 4 → 5 → 6 → 7 → 8 → 9 → 10
N=2, M=3
output: 1 → 2 → 3 → 6 → 7 → 8
Example-2
input: 1 → 2 → 3 → 4 → 5 → 6 → 7 → 8 → 9 → 10 → 11
N=3, M=3
output: 1 → 2 → 3 → 7 → 8 → 9
Code:
class Node:
def _init_(self,data):
self.data = data
self.next = None
class List:
def _init_(self):
self.head = None
def push(self,new_data):
new_node = Node(new_data)
new_node.next = self.head

7. Aastha Shah_Ganpat University
self.head = new_node
def printList(self):
temp = self.head
while(temp):
print(temp.data, end=" ")
temp = temp.next
def skipMdeleteN(self,M,N):
curr = self.head
while(curr):
for count in range(1,M):
if curr is None:
return
curr = curr.next
if curr is None:
return
t = curr.next
for count in range(1,N+1):
if t is None:

8. Aastha Shah_Ganpat University
break
t = t.next
curr.next = t
curr = t
llist = List()
M = 2
N = 3
llist.push(10)
llist.push(9)
llist.push(8)
llist.push(7)
llist.push(6)
llist.push(5)
llist.push(4)
llist.push(3)
llist.push(2)
llist.push(1)
print("M = %d, N = %dnGiven linked list is:" %(M,N))
llist.printList()
print()

9. Aastha Shah_Ganpat University
llist.skipMdeleteN(M,N)
print("nLinked list after deletion is")
list.printList()

10. Aastha Shah_Ganpat University
Que 4. Write a program or algorithm for Two Elements whose sum is closest to
zero. [5 marks]
Example
You are given an array [-23, 12, -35, 45, 20, 36] then the two elements would be -35 &
36 as their pair sum is 1 which is closest to 0
Code:
def minSum(arr,arr_size):
inv_count = 0
if arr_size < 2:
print("Invalid Input")
return
min_l = 0
min_r = 1
min_sum = arr[0] + arr[1]
for l in range (0,arr_size,-1):
for r in range(l + 1, arr_size):
sum = arr[l] + arr[r]
if abs(min_sum) > abs(sum):
min_sum = sum
min_l = l
min_r = r

11. Aastha Shah_Ganpat University
print("Two elements whose sum is closest to 0 are: " + arr[min_l], + "and" +
arr[min_r])
arr = [-23, 12, -35, 45, 20, 36]
minSum(arr,6);

12. Aastha Shah_Ganpat University
Que 5. From the following table, write a SQL query to find customers who are
either from the city 'New York' or who do not have a grade greater than 100.
Return customer_id, cust_name, city, grade, and salesman_id.
Query:
SELECT * FROM customer_id WHERE NOT(city = 'New York' OR grade>100);

13. Aastha Shah_Ganpat University
Que 6. From the above customer table, write a SQL query to determine the
number of customers who received at least one grade for their activity.
Query:
SELECT COUNT (ALL grade) FROM customer_id