#3582

Easy

LeetCode Problem Workspace

Generate Tag for Video Caption

Transform a video caption into a valid hashtag by simulating capitalization rules and truncation for long words efficiently.

string simulation

Problem Statement

Given a string caption representing a video's caption, generate a valid tag by following a specific capitalization and formatting procedure. The tag must start with a '#' and use camel-case capitalization for words after the first word.

You must handle captions up to 150 characters, ensuring that any word exceeding the tag limit is truncated. The resulting string should combine all words according to the rules, producing a single hashtag-ready string.

Examples

Example 1

Input: caption = "Leetcode daily streak achieved"

Output: "#leetcodeDailyStreakAchieved"

The first letter for all words except "leetcode" should be capitalized.

Example 2

Input: caption = "can I Go There"

Output: "#canIGoThere"

The first letter for all words except "can" should be capitalized.

Example 3

Input: caption = "hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh"

Output: "#hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh"

Since the first word has length 101, we need to truncate the last two letters from the word.

Constraints

1 <= caption.length <= 150
caption consists only of English letters and ' '.

Solution Approach

Split Caption and Process Words

Start by splitting the caption into individual words. Keep the first word lowercase, then capitalize the first letter of each subsequent word to simulate camel-case formatting.

Concatenate and Add Hashtag

Join all processed words together into a single string and prepend the '#' symbol. This step ensures the tag meets the required format for video captions.

Handle Length Constraints

Check if the resulting tag exceeds the maximum allowed length. If necessary, truncate excess characters from the end of the string while preserving the correct capitalization pattern.

Complexity Analysis

Metric	Value
Time	Depends on the final approach
Space	Depends on the final approach

Time complexity is O(n) where n is the length of the caption because each character is processed once. Space complexity is O(n) for storing words and the final tag string.

What Interviewers Usually Probe

Check how you handle the first word versus subsequent words for capitalization.
Confirm proper truncation behavior when the tag length exceeds allowed limits.
Ask how the simulation of camel-case formatting is implemented efficiently.

Common Pitfalls or Variants

Common pitfalls

Forgetting to lowercase the first word, which violates the hashtag style.
Incorrectly capitalizing words that should remain lowercase or skipping truncation.
Concatenating words without handling spaces, which breaks the simulation.

Follow-up variants

Allow numeric characters in captions and simulate proper capitalization with numbers.
Support multiple spaces between words and ensure the tag ignores extra spaces.
Generate hashtags using different capitalization rules, like all uppercase after the first word.

FAQ

What is the easiest approach to generate a tag from a video caption?

Split the caption into words, lowercase the first word, capitalize the first letters of the rest, join them, and prepend '#'.

How does the simulation pattern apply to this problem?

The simulation involves iterating over words, applying capitalization rules, and truncating if necessary, mimicking real hashtag generation.

Do spaces in the caption affect the resulting tag?

No, spaces are removed in the final tag; only capitalization rules and truncation matter.

How should very long words be handled?

Truncate the word to fit within the maximum tag length, preserving the correct capitalization sequence.

Is the first word always lowercase in the hashtag?

Yes, to follow camel-case simulation rules, the first word remains lowercase regardless of its original casing.

terminal

Solution

Solution 1: Simulation

We first split the title string into words, then process each word. The first word should be all lowercase, while for the subsequent words, the first letter is capitalized and the rest are lowercase. Next, we concatenate all the processed words and add a # symbol at the beginning. Finally, if the generated tag exceeds 100 characters in length, we truncate it to the first 100 characters.

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class Solution:
    def generateTag(self, caption: str) -> str:
        words = [s.capitalize() for s in caption.split()]
        if words:
            words[0] = words[0].lower()
        return "#" + "".join(words)[:99]

Continue Practicing

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