Please find below some of the common interview questions asked and their solutions related to coding in interviews:
Expand All Questions Collapse All QuestionsQuestion 1: How to reverse a string in python?
Answer: There are many ways to reverse a string in python:
- Slicing syntax of strings:
def reverse(stri):
return stri[::-1]
print(reverse("string")) # gnirts
2. Using list reverse() function and join:
def reverse(stri):
stri = [ s for s in stri ] # stri = list(stri)
stri.reverse()
return (''.join(stri))
print(reverse("string")) # gnirts
3. Using reversed() in=built funciton:
def reverse(stri):
l = list(reversed(stri))
return ''.join(l)
print(reverse("string")) # gnirts
Question 2: Write a function to find factorial of a number and optimize it using generator by storing the generate values.
Answer:
memory={}
def decorater_memo(fibonacci):
def memoize(num):
if num in memory.keys():
return memory[num]
else:
memory[num]=fibonacci(num)
return memory[num]
return memoize
@decorater_memo
def fibonacci(num):
if num <0:
return 0
elif num==0:
return 1
else:
return fibonacci(num-2)+fibonacci(num-1)
for i in range(100):
#print(memory)
print(fibonacci(i))
Question 3: Given an array of integers and a target sum, find all pairs of integers in the array that sum up to the target.
Input: nums = [2,7,11,15], target = 9
Output: [0,1]
Answer: We will create a function which will take a list and target as input then check every pair of elements and their sum against target value:
def pair_sum(arr,target):
for i in range(len(arr)):
for j in range(i,len(arr)):
if i != j and arr[i] + arr[j] == target:
print([i,j])
pair_sum([2,7,11,15], 9)
Question 4: Write a Python program to print a Triangle pattern
Input: 5
Output:
Answer:
def pattern(num):
for i in range(num):
print("* "*(num-i),end="")
print(" "*((i*2)+1),end="")
print("* "*(num-i),end="")
print()
pattern(5)
Following is single line print statement:
def pattern(num):
print( '\n'.join([(" "*((i*2)+1)).join(["* "*(num-i),"* "*(num-i)]) for i in range(num) ]))
pattern(5)
Question 5: Count number of vowels in a string in python.
Answer: Following code can count the number of vowels in python string:
def count_vowels(s):
c = {}
for x in s:
if x in 'aeiouAEIOU':
if(x in c.keys()):
c[x] += 1
else:
c[x] = 1
return sum(c.values())
print(count_vowels("this is a string")) #4
using string.count() and dict comprehension:
def count_vowels(s):
c = { x: s.count(x) for x in 'aeiouAEIOU'}
return sum(c.values())
print(count_vowels("this is a string")) #4
using collections.Counter() and filter function:
from collections import Counter
def count_vowels(s):
c = Counter(s)
c = dict(filter(lambda x: x[0] in 'aeiouAEIOU' ,c.items()))
return sum(c.values())
print(count_vowels("this is a string")) #4
Note: we have calculated each character occurrence separately and then added the values to provide two types of solutions at the same time. first separate count and second total count of vowels.
