Python Hacker Rank Challenges – Solutions

1. Task

print Hello, World! on your screen

def main():
my_string = “Hello, World!”
print (my_string)

if __name__ == ‘__main__’:
main()

2. Task

Given an integer, , perform the following conditional actions:

• If is odd, print Weird
• If is even and in the inclusive range of to , print Not Weird
• If is even and in the inclusive range of to , print Weird
• If is even and greater than , print Not Weird

Input Format

A single line containing a positive integer, .

Constraints

Output Format

Print Weird if the number is weird. Otherwise, print Not Weird.

import math
import os
import random
import re
import sys

def main():
n = int(raw_input().strip())

if n % 2 == 1:
print (“Weird”)
elif n >= 6 and n <=20:
print (“Weird”)
else: print (“Not Weird”)

if __name__ == ‘__main__’:
main()

3. Task

The provided code stub reads two integers from STDIN, and . Add code to print three lines where:

1. The first line contains the sum of the two numbers.
2. The second line contains the difference of the two numbers (first – second).
3. The third line contains the product of the two numbers.

if __name__ == ‘__main__’:
a = int(raw_input())
b = int(raw_input())

print a + b
print a – b
print a * b

4. Task

The provided code stub reads two integers, and , from STDIN.

Add logic to print two lines. The first line should contain the result of integer division, // . The second line should contain the result of float division, / .

No rounding or formatting is necessary.
from __future__ import division

def main():
a = int(raw_input())
b = int(raw_input())
print a // b
print a / b

if __name__ == ‘__main__’:
main()

5. Task

The provided code stub reads and integer, , from STDIN. For all non-negative integers , i < n , print i ** 2 .

def main():
n = int(input())

i = 0

while i < n:
print (i ** 2)
i = i + 1

if __name__ == ‘__main__’:
main()

6. Leap Year

An extra day is added to the calendar almost every four years as February 29, and the day is called a leap day. It corrects the calendar for the fact that our planet takes approximately 365.25 days to orbit the sun. A leap year contains a leap day.

In the Gregorian calendar, three conditions are used to identify leap years:

• The year can be evenly divided by 4, is a leap year, unless:
  • The year can be evenly divided by 100, it is NOT a leap year, unless:
    • The year is also evenly divisible by 400. Then it is a leap year.

This means that in the Gregorian calendar, the years 2000 and 2400 are leap years, while 1800, 1900, 2100, 2200, 2300 and 2500 are NOT leap years. Source

Task

Given a year, determine whether it is a leap year. If it is a leap year, return the Boolean True, otherwise return False.

Note that the code stub provided reads from STDIN and passes arguments to the is_leap function. It is only necessary to complete the is_leap function.

def is_leap(year):
leap = False

if year % 4 == 0 and year % 100 != 0:
leap = True
elif year % 100 == 0 and year % 400 == 0:
leap = True
else: leap = False

return leap
year = int(input())
print(is_leap(year))

modify the function a bit as below to test in spyder

year = 2100 # testing year

def is_leap(year):
leap = False

if year % 4 == 0 and year % 100 != 0:
leap = True
elif year % 100 == 0 and year % 400 == 0:
leap = True
else: leap = False

return leap

print (is_leap(year))

7. Print Function – List —- Hint ==> print (*list, sep=””)

The included code stub will read an integer, , from STDIN.

Without using any string methods, try to print the following:

Note that “” represents the consecutive values in between.

if __name__ == ‘__main__’:
n = int(input())
i = 1
list = []
while i <= n:
list.append(i)
i = i +1
print (*list, sep=””)

8. Regular Expression example

Write a simple program to check if the set of characters contain a-zA-Z0-9

import re

if __name__ == ‘__main__’:

def checkChar(string):
result = re.match(r'[^a-zA-Z0-9.]’, string)
return not bool(result)

print(checkChar(“ABCDEabcde12345”))
print(checkChar(“*&^%$#@!)”))

9. Regular Expression example 2

import re

if __name__ == ‘__main__’:

def checkChar(string):
patterns = ‘ab*’
if re.search(patterns, string):
return ‘found a match’
else: return ‘found not match’

print (checkChar(‘abbb’))
print (checkChar(‘ab’))
print (checkChar(‘a’))
print (checkChar(‘ccc’))

10. Validating Roman Numeral

You are given a string, and you have to validate whether it’s a valid Roman numeral. If it is valid, print True. Otherwise, print False. Try to create a regular expression for a valid Roman numeral.

Input Format

A single line of input containing a string of Roman characters.

Output Format

Output a single line containing True or False according to the instructions above.

Constraints

The number will be between 1 and 3999 (both included).

regex_pattern = r”(^M{0,3})(CM|CD|D?C{0,3})(XC|XL|L?X{0,3})(IX|IV|V?I{0,3})$” # Do not delete ‘r’.

import re
print(str(bool(re.match(regex_pattern, input()))))

11. Validating Phone Number

How to read from stdin
https://www.geeksforgeeks.org/take-input-from-stdin-in-python/

Concept

A valid mobile number is a ten digit number starting with a 7,8,9

Sample Input
2
9587456281
1252478965

Sample Output
YES
NO

# Enter your code here. Read input from STDIN. Print output to STDOUT

import sys
import re
if __name__ == ‘__main__’:
for linenum, line in enumerate(sys.stdin):
if linenum != 0:
patterns = r’^[7,8,9][0-9]{9}$’
result = bool(re.match(patterns, line))

if result == True:
print(‘YES’)
else: print(‘NO’)

12. Validating and Parsing email addresses

A valid email address meets the following criteria:

• It’s composed of a username, domain name, and extension assembled in this format: username
• The username starts with an English alphabetical character, and any subsequent characters consist of one or more of the following: alphanumeric characters, -,., and _.
• The domain and extension contain only English alphabetical characters.
• The extension is , , or characters in length.

Given pairs of names and email addresses as input, print each name and email address pair having a valid email address on a new line.

Hint: Try using Email.utils() to complete this challenge. For example, this code:
import email.utils

print email.utils.parseaddr(‘DOSHI <[email protected]>’)
print email.utils.formataddr((‘DOSHI’, ‘[email protected]’))

produces this output:
(‘DOSHI’, ‘[email protected]’)
DOSHI <[email protected]>

Input Format

The first line contains a single integer, , denoting the number of email address.Each line of the subsequent lines contains a name and an email address as two space-separated values following this format:
name <[email protected]>

Constraints
0 < n < 100

Output Format

Print the space-separated name and email address pairs containing valid email addresses only. Each pair must be printed on a new line in the following format:
name <[email protected]>

You must print each valid email address in the same order as it was received as input.

Sample Input
2
DEXTER <[email protected]>
VIRUS <virus!@variable.:p>

Sample Output
DEXTER <[email protected]>

Solutions
# Enter your code here. Read input from STDIN. Print output to STDOUT
import sys
import re
import email.utils
for linenum, line in enumerate(sys.stdin):
if linenum != 0:
patterns = r’^[a-zA-Z]{1}[a-zA-Z0-9._-]+[@]{1}[a-zA-Z]+[.]{1}[a-zA-Z]{1,3}$’
nameEmail = email.utils.parseaddr(line)
result = bool(re.match(patterns, nameEmail[1]))

if result == True:
print (email.utils.formataddr(nameEmail))

Modify the solution and run in spyder

import re
import email.utils

if __name__ == “__main__”:

line = input(“Please input name, <email address>:”)

patterns = ‘^[a-zA-Z]{1}[a-zA-Z0-9-._]+[@]{1}[a-zA-Z]+[.]{1}[a-zA-Z]{1,3}$’
nameEmail = email.utils.parseaddr(line)
result = bool(re.match(patterns, nameEmail[1]))

if result == True:
print (email.utils.formataddr(nameEmail))

13. Hex Color Code

CSS colors are defined using a hexadecimal (HEX) notation for the combination of Red, Green, and Blue color values (RGB).

Specifications of HEX Color Code

■ It must start with a ‘#’ symbol.■ It can have or digits.■ Each digit is in the range of to . ( and ).■ letters can be lower case. ( and are also valid digits).

Examples
Valid Hex Color Codes
#FFF
#025
#F0A1FB

Invalid Hex Color Codes
#fffabg
#abcf
#12365erff

Solution
# Enter your code here. Read input from STDIN. Print output to STDOUT

import re, sys
[print(j) for i in sys.stdin for j in re.findall(‘[s:](#[a-f0-9]{6}|#[a-f0-9]{3})’, i, re.I)]