Python Practice Questions

Topic-based coding problems with sample test cases — build confidence step by step.

Strings Practice

String manipulation, slicing, formatting and text processing problems.

1
Reverse a String
Easy
Write a program to reverse the given string and print it.
Input Format
A single line containing a string S.
Output Format
Print the reversed string.
Sample Test Cases
Sample Input 1
hello
Sample Output 1
olleh
Sample Input 2
racecar
Sample Output 2
racecar
Sample Input 3
Python
Sample Output 3
nohtyP
2
Count Vowels in a String
Easy
Write a program to count the number of vowels (a, e, i, o, u) in a given string. Case-insensitive.
Input Format
A single line containing a string S.
Output Format
Print a single integer — the number of vowels.
Sample Test Cases
Sample Input 1
education
Sample Output 1
5
Sample Input 2
Hello
Sample Output 2
2
Sample Input 3
Python
Sample Output 3
1
3
Check Palindrome String
Easy
Write a program to check whether the given string reads the same forwards and backwards.
Input Format
A single line containing a string S.
Output Format
Print YES if palindrome, else NO.
Sample Test Cases
Sample Input 1
madam
Sample Output 1
YES
Sample Input 2
racecar
Sample Output 2
YES
Sample Input 3
hello
Sample Output 3
NO
4
Convert to Uppercase
Easy
Write a program to convert the entire given string to uppercase.
Input Format
A single line containing a string S.
Output Format
Print the string in uppercase.
Sample Test Cases
Sample Input 1
hello world
Sample Output 1
HELLO WORLD
Sample Input 2
Tech Bridge
Sample Output 2
TECH BRIDGE
Sample Input 3
abc123
Sample Output 3
ABC123
5
Length of String
Easy
Write a program to find and print the length of the given string.
Input Format
A single line containing a string S.
Output Format
Print a single integer — the length of S.
Sample Test Cases
Sample Input 1
TechBridge24
Sample Output 1
12
Sample Input 2
Hi
Sample Output 2
2
Sample Input 3
Hello World
Sample Output 3
11
6
Remove Spaces
Easy
Write a program to remove all whitespace characters from the given string.
Input Format
A single line containing a string S with spaces.
Output Format
Print the string without any spaces.
Sample Test Cases
Sample Input 1
hello world python
Sample Output 1
helloworldpython
Sample Input 2
a b c
Sample Output 2
abc
Sample Input 3
python
Sample Output 3
python
7
First and Last Character
Easy
Write a program to print the first and last character of the given string on separate lines.
Input Format
A single line containing a string S.
Output Format
Print the first character on line 1 and the last character on line 2.
Sample Test Cases
Sample Input 1
python
Sample Output 1
p
n
Sample Input 2
hello
Sample Output 2
h
o
Sample Input 3
ab
Sample Output 3
a
b
8
Count Words in a String
Easy
Write a program to count the number of words in the given string. Words are separated by single spaces.
Input Format
A single line containing a string S.
Output Format
Print a single integer — the number of words.
Sample Test Cases
Sample Input 1
I love python programming
Sample Output 1
4
Sample Input 2
one two three
Sample Output 2
3
Sample Input 3
python
Sample Output 3
1
9
Check if String Contains Digit
Easy
Write a program to check whether the given string contains at least one digit.
Input Format
A single line containing a string S.
Output Format
Print YES if it contains a digit, else NO.
Sample Test Cases
Sample Input 1
python3
Sample Output 1
YES
Sample Input 2
hello
Sample Output 2
NO
Sample Input 3
123
Sample Output 3
YES
10
Swap Case of Characters
Easy
Write a program to swap the case of each character (lower to upper and vice versa) in the given string.
Input Format
A single line containing a string S.
Output Format
Print the string with swapped case.
Sample Test Cases
Sample Input 1
HelloWorld
Sample Output 1
hELLOwORLD
Sample Input 2
PYTHON
Sample Output 2
python
Sample Input 3
aBc
Sample Output 3
AbC
1
Count Each Character Frequency
Medium
Write a program to count the frequency of each character in the given string.
Input Format
A single line containing a string S.
Output Format
Print each character and its count as char: count, one per line.
Sample Test Cases
Sample Input 1
abracadabra
Sample Output 1
a: 5
b: 2
c: 1
d: 1
r: 2
Sample Input 2
hello
Sample Output 2
h: 1
e: 1
l: 2
o: 1
Sample Input 3
aabb
Sample Output 3
a: 2
b: 2
2
Remove Duplicate Characters
Medium
Write a program to remove duplicate characters from the string while preserving the order of first occurrence.
Input Format
A single line containing a string S.
Output Format
Print the string after removing duplicates.
Sample Test Cases
Sample Input 1
programming
Sample Output 1
progamin
Sample Input 2
banana
Sample Output 2
ban
Sample Input 3
hello
Sample Output 3
helo
3
Check Anagram Strings
Medium
Write a program to check whether two strings are anagrams of each other.
Input Format
First line: string A. Second line: string B.
Output Format
Print YES if anagrams, else NO.
Sample Test Cases
Sample Input 1
listen
Sample Output 1
silent
Sample Input 2
listen
silent
Sample Output 2
YES
Sample Input 3
hello
world
Sample Output 3
NO
Constraints
YES
4
Reverse Words in a String
Medium
Write a program to reverse the order of words in the given sentence.
Input Format
A single line containing a string S with words separated by single spaces.
Output Format
Print the sentence with words reversed.
Sample Test Cases
Sample Input 1
I love python
Sample Output 1
python love I
Sample Input 2
hello world
Sample Output 2
world hello
Sample Input 3
a b c
Sample Output 3
c b a
5
Longest Word in a String
Medium
Write a program to find and print the longest word in the given sentence. If there are multiple, print the first one.
Input Format
A single line containing a string S.
Output Format
Print the longest word.
Sample Test Cases
Sample Input 1
python is a powerful language
Sample Output 1
powerful
Sample Input 2
short and verylong
Sample Output 2
verylong
Sample Input 3
a bb ccc
Sample Output 3
ccc
6
Check Substring Present
Medium
Write a program to check whether a substring is present inside the main string.
Input Format
First line: string S. Second line: substring T.
Output Format
Print YES if T is present in S, else NO.
Sample Test Cases
Sample Input 1
Hello World
Sample Output 1
World
Sample Input 2
Hello World
lo Wo
Sample Output 2
YES
Sample Input 3
abc
xyz
Sample Output 3
NO
Constraints
YES
7
Count Consonants
Medium
Write a program to count the number of consonants in the given string.
Input Format
A single line containing a string S.
Output Format
Print a single integer — the number of consonants.
Sample Test Cases
Sample Input 1
programming
Sample Output 1
9
Sample Input 2
hello
Sample Output 2
3
Sample Input 3
aeiou
Sample Output 3
0
8
Replace All Spaces with Hyphen
Medium
Write a program to replace every space in the given string with a hyphen (-).
Input Format
A single line containing a string S.
Output Format
Print the modified string.
Sample Test Cases
Sample Input 1
hello world python
Sample Output 1
hello-world-python
Sample Input 2
a b
Sample Output 2
a-b
Sample Input 3
x  y
Sample Output 3
x--y
9
Capitalize First Letter of Each Word
Medium
Write a program to capitalize the first letter of every word in the given string.
Input Format
A single line containing a string S.
Output Format
Print the string with each word capitalized.
Sample Test Cases
Sample Input 1
python is great
Sample Output 1
Python Is Great
Sample Input 2
hello world
Sample Output 2
Hello World
Sample Input 3
a b
Sample Output 3
A B
10
Check if String is Pangram
Medium
Write a program to check whether the given string is a pangram (contains every letter a–z at least once).
Input Format
A single line containing a string S.
Output Format
Print YES if pangram, else NO.
Sample Test Cases
Sample Input 1
The quick brown fox jumps over the lazy dog
Sample Output 1
YES
Sample Input 2
hello
Sample Output 2
NO
Sample Input 3
abcdefghijklmnopqrstuvwxyz
Sample Output 3
YES
1
Longest Substring Without Repeating Characters
Hard
Write a program to find the length of the longest substring without repeating characters.
Input Format
A single line containing a string S.
Output Format
Print a single integer — the length of the longest substring.
Sample Test Cases
Sample Input 1
abcabcbb
Sample Output 1
3
Sample Input 2
bbbbb
Sample Output 2
1
Sample Input 3
pwwkew
Sample Output 3
3
2
Minimum Window Substring
Hard
Write a program to find the smallest substring in S that contains all characters of string T.
Input Format
First line: string S. Second line: string T.
Output Format
Print the smallest window substring; print -1 if no such window exists.
Sample Test Cases
Sample Input 1
ADOBECODEBANC
Sample Output 1
ABC
Sample Input 2
a
aa
Sample Output 2
NO
Sample Input 3
abc
b
Sample Output 3
b
Constraints
BANC
3
String Rotation Check
Hard
Write a program to check whether string B is a rotation of string A.
Input Format
First line: string A. Second line: string B.
Output Format
Print YES if B is a rotation of A, else NO.
Sample Test Cases
Sample Input 1
ABCD
Sample Output 1
CDAB
Sample Input 2
ABCD
BCDA
Sample Output 2
YES
Sample Input 3
ABCD
ABCD
Sample Output 3
YES
Constraints
YES
4
Longest Palindromic Substring
Hard
Write a program to find the longest palindromic substring in the given string.
Input Format
A single line containing a string S.
Output Format
Print the longest palindromic substring.
Sample Test Cases
Sample Input 1
babad
Sample Output 1
bab
Sample Input 2
cbbd
Sample Output 2
bb
Sample Input 3
a
Sample Output 3
a
5
String to Integer (atoi)
Hard
Write a program to convert the given numeric string to an integer without using int(). Handle optional leading + or - sign.
Input Format
A single line containing a numeric string S.
Output Format
Print the integer value.
Sample Test Cases
Sample Input 1
-12345
Sample Output 1
-12345
Sample Input 2
+123
Sample Output 2
123
Sample Input 3
007
Sample Output 3
7
6
Print All Substrings of a String
Hard
Write a program to print all substrings of the given string, one per line, in order of increasing length.
Input Format
A single line containing a string S.
Output Format
Print all substrings, one per line.
Sample Test Cases
Sample Input 1
abc
Sample Output 1
a
b
c
ab
bc
abc
Sample Input 2
ab
Sample Output 2
a
b
ab
Sample Input 3
xyz
Sample Output 3
x
y
z
xy
yz
xyz
7
Group Anagrams Together
Hard
Write a program to group words that are anagrams of each other from a list of words.
Input Format
First line: integer N. Second line: N space-separated words.
Output Format
Print each group as a space-separated line, groups in order of first appearance.
Sample Test Cases
Sample Input 1
5
eat tea tan ate nat
Sample Output 1
eat tea ate
tan nat
Sample Input 2
4
dog god act
Sample Output 2
dog god
act
Sample Input 3
3
cat act tac
Sample Output 3
cat act tac
8
First Non-Repeating Character
Hard
Write a program to find the first non-repeating character in the given string.
Input Format
A single line containing a string S.
Output Format
Print the first non-repeating character, or -1 if none exists.
Sample Test Cases
Sample Input 1
swiss
Sample Output 1
w
Sample Input 2
aabbcc
Sample Output 2
-1
Sample Input 3
xxyz
Sample Output 3
y
9
Compress the String (Run-Length)
Hard
Write a program to compress the string using run-length encoding: char followed by its count.
Input Format
A single line containing a string S.
Output Format
Print the compressed string.
Sample Test Cases
Sample Input 1
aaabbcccc
Sample Output 1
a3b2c4
Sample Input 2
aab
Sample Output 2
a2b1
Sample Input 3
aaa
Sample Output 3
a3
10
Zigzag String Conversion
Hard
Write a program to convert the given string into a zigzag pattern with numRows rows and read it row by row.
Input Format
First line: string S. Second line: integer numRows.
Output Format
Print the zigzag-converted string.
Sample Test Cases
Sample Input 1
PAYPALISHIRING
Sample Output 1
3
Sample Input 2
AB
1
Sample Output 2
AB
Sample Input 3
ABCD
2
Sample Output 3
ACBD
Constraints
PAHNAPLSIIGYIR