Interview Questions Asked in TCS & Infosys

Interview Questions Asked in TCS & Infosys

(You will get the video explanation at the bottom of page)

1) Prime Numbers using Sieve of Eratosthenes:

# https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes

def prime(n):
    prime_list = [True for i in range(n + 1)]
    p = 2
    while p * p <= n:
        if prime_list[True]:
            for i in range(p * 2, n + 1, p):
                prime_list[i] = False

        p += 1
    prime_list[0] = False
    prime_list[1] = False
    return prime_list

ans = prime(20)
for i in range(len(ans)):
    if ans[i]:
        print(i, end = " ")

2) Frequency Count:

s = 'aabbcaabc'

#Using Counter
from collections import Counter
freq = Counter(s)
print(freq)


#Using Dictionary 
d = dict.fromkeys(s, 0)
print(d)
for i in s:
    d[i] = d[i] + 1

print("Frequency :", d)

3) Nth Largest Number:

val = [4, 9, 5, 6, 1, 2, 7]
import heapq
heapq.heapify(val)
print(heapq.nlargest(2, val))

4) Combinations:

comb = [1, 2, 3]
from itertools import combinations

#print(list(combinations(comb, 1)))
ans = []
for i in range(1, len(comb) + 1):
    ans.append(list(combinations(comb, i)))
print(and)

#Binary
bin_val = [str(bin(i))[2:] for i in range(1, 2 ** len(comb))]
val = list(map(str,comb[:]))
print(bin_val)

for i in bin_val:
    temp = ''
    for j in range(len(i)):
        if i[j] == '1':
            temp += str(comb[j])
    val.append(temp)

print(set(val))

5) Middle Element of Linked List in Single Loop:

class Node:  
    def __init__(self, data, next = None):  
        self.data = data  
        self.next = next                

def print_List(List):
    l = []
    while List != None:
        l.append(List.data)
        List = List.next

    print(l)
              
array = [1, 2, 3, 4, 5, 6, 7]
List = None

for i in array:
    List = Node(i, List)
#print_List(List)
ptr1 = List
count = 1

while count != len(array) - 1:
    if count & 1 == 1:
        ptr1 = ptr1.next
    count += 1
print(ptr1.data)