Python Coding:Reverse Words in a Sentence Without Using split()! 🔄
In this Python tutorial, we solve a classic coding problem: Reversing words in a sentence without using the built-in split() function. This is a common interview question that tests your understanding of string manipulation and data structures like lists.
Instead of relying on Python’s split(), we manually extract words and reverse them, achieving O(N) time complexity.
Problem Breakdown:
📌 Problem Statement:
Given a sentence (a string of words separated by spaces), reverse the order of words without using split().
Example:
Input: "Hello world from Python"
Output: "Python from world Hello"
Approach (Without Using split())
Extract Words Manually:
Iterate through the string character by character.
Collect non-space characters into a temporary string.
When a space is encountered, store the completed word in a list.
Reverse the Word Order:
Pop words from the list one by one and construct the reversed sentence.
Python Code Implementation:
def reverse_words(sentence):
words, temp, result = [], "", ""
Extract words manually
for char in sentence + " ": # Adding space at the end ensures last word is processed
if char == " ":
if temp:
words.append(temp) # Store word in list
temp = "" # Reset temporary word storage
else:
temp += char # Keep building the word
Reverse the word order
while words:
result += words.pop() + " " # Pop words in reverse order
return result.strip() # Remove trailing space
✅ Test Cases
print(reverse_words("Hello world from Python"))
Output: "Python from world Hello"
print(reverse_words(" Python is awesome "))
Output: "awesome is Python"
print(reverse_words("Coding is fun"))
Output: "fun is Coding"
🔍 Explanation of the Code:
Extract words manually:
Traverse the string character by character.
When encountering a space, store the current word.
Reset the temporary variable for the next word.
Reverse the words using a list:
Use .pop() to construct the reversed sentence.
Complexity Analysis:
✅ Time Complexity: O(N) – We traverse the string only once.
✅ Space Complexity: O(N) – We store words in a list before reversing them.
Edge Cases Considered:
✅ Multiple spaces between words: " Python is awesome "
✅ Trailing and leading spaces: " Hello world "
✅ Single word: "Python"
✅ Empty string: ""
Why Is This Useful?
Avoids using built-in functions like split().
Improves understanding of manual string parsing.
Optimized approach with minimal extra space.
🔑 Key Takeaways:
Manually extract words instead of using split().
Use a list to store words and pop them in reverse order.
Handles extra spaces efficiently.
Optimized for interview scenarios where built-in functions are restricted.
Python, Python coding, reverse words in a sentence, Python string manipulation, reverse words without split, Python interview questions, coding interview, Python algorithm, string processing, reverse a sentence, Python tricks
#youtube
#youtubeshorts
#yiutubeshort
#youtubeshort
#youtuber
#trending #trend
#trendingshorts
#trenfingshortvideo
#trendingvideo
#viralvideo
#viralshort
#viralshorts
#viral_video
#Python #PythonCoding #StringManipulation #ReverseWords #PythonInterview #DataStructures #CodingInterview #PythonTricks #StringProcessing #python
#interview