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🔔 Prepare Notification Message with Length Limit in Python

📋 Problem Overview

You're building a notification system where messages are shown on a mobile screen. The message must not exceed K characters, and it must be cropped properly if it’s too long — meaning only whole words are kept, and an ellipsis ("...") is added when cropping occurs.

✨ Cropping Rules

Given:

• message: a space-separated string.
• K: the character limit for the notification.

Produce:

• A string of at most K characters that:
• Ends with " ..." if cropped (note: a space before the three dots).
• Is as long as possible without breaking words.
• If the whole message fits, return it as is.
• If no word fits, return only "..." (3 dots, no space before).

✅ Examples

MessageKOutput"And now here is my secret"15"And now ...""There is an animal with four legs"15"There is an ...""super dog"4"...""how are you"20"how are you"

🧠 Algorithm Breakdown

1. Check edge case: If K < 3, return "..." right away.
2. Split the message into words.
3. Build the message one word at a time, stopping when adding another word would exceed the limit.
4. If cropping was necessary, check if there's room for " ..." and add it properly.
5. If no word fits, return only "...".

🧑‍💻 Python Implementation

python

def solution(message, K):
    if K < 3:
        return "..."

    words = message.split()
    notification = ""
    
    for word in words:
        if notification:
            # Check space + word
            if len(notification) + len(word) + 1 <= K:
                notification += " " + word
            else:
                break
        else:
            # First word (no leading space)
            if len(word) <= K:
                notification = word
            else:
                break

    # Full message fits
    if len(notification) == len(message):
        return notification

    # If no words fit
    if not notification:
        return "..."

    # Ensure we can add " ..."
    if len(notification) + 4 <= K:
        return notification + " ..."
    else:
        # Edge case: crop an extra word if needed to fit the ellipsis
        words = notification.split()
        trimmed = ""
        for word in words[:-1]:
            if not trimmed:
                test = word
            else:
                test = trimmed + " " + word
            if len(test) + 4 <= K:
                trimmed = test
            else:
                break
        return trimmed + " ..." if trimmed else "..."

📌 Important Notes

• " ..." is 4 characters including the space.
• The logic handles the corner case where no word fits within the limit.
• This is a greedy solution — it adds as many full words as possible from the beginning.

🧪 Test It!

python

print(solution("And now here is my secret", 15))         # "And now ..."
print(solution("There is an animal with four legs", 15)) # "There is an ..."
print(solution("super dog", 4))                          # "..."
print(solution("how are you", 20))                       # "how are you"