Acronym Generator - Problem

Generate an acronym from a given phrase by taking the first letter of each word and converting it to uppercase.

For example, 'Portable Network Graphics' becomes 'PNG'.

Rules:

Split the phrase into words by spaces
Take the first character of each word
Convert all letters to uppercase
Join them together without spaces

Input & Output

Example 1 — Basic Phrase

$ Input: phrase = "Portable Network Graphics"

› Output: "PNG"

💡 Note: Take first letter of each word: 'P' from Portable, 'N' from Network, 'G' from Graphics, result is 'PNG'

Example 2 — Single Word

$ Input: phrase = "Hello"

› Output: "H"

💡 Note: Only one word 'Hello', so acronym is just 'H'

Example 3 — Multiple Spaces

$ Input: phrase = "World Wide Web"

› Output: "WWW"

💡 Note: Extra spaces are ignored, words are 'World', 'Wide', 'Web', acronym is 'WWW'

Constraints

1 ≤ phrase.length ≤ 1000
phrase consists of letters and spaces
phrase contains at least one letter

Visualization

Tap to expand

Asked in

G Google 25 a Amazon 18 M Microsoft 15 🍎 Apple 12

The key insight is to identify word boundaries and extract the first alphabetic character from each word. The optimal approach uses either character-by-character processing with a word boundary flag or splitting into words first. Time: O(n), Space: O(k) where k is the number of words.

Common Approaches

✓ Brute Force - Character by Character

⏱️ Time: O(n) Space: O(k)

Iterate through each character in the phrase, tracking when we're at the beginning of a word (first character or after a space), then collect and uppercase those characters.

Split and Extract - Two Pass

⏱️ Time: O(n) Space: O(n)

Split the phrase by spaces to get individual words, then iterate through words and take the first character of each word, converting to uppercase.

Brute Force - Character by Character — Algorithm Steps

Step 1: Initialize empty result string and set atWordStart to true
Step 2: Loop through each character in the phrase
Step 3: If atWordStart and character is a letter, add uppercase version to result
Step 4: Update atWordStart flag based on whether current character is a space

Visualization

Tap to expand

Step-by-Step Walkthrough

Initialize

Start with empty result and atWordStart=true

Process Each Character

Check if at word start and is letter

Build Acronym

Collect uppercase first letters

Code -

solution.c — C

#include <stdio.h>
#include <string.h>
#include <ctype.h>

char* solution(char* phrase) {
    static char result[1000];
    int resultIdx = 0;
    int atWordStart = 1;
    
    for (int i = 0; phrase[i] != '\0'; i++) {
        if (atWordStart && isalpha(phrase[i])) {
            result[resultIdx++] = toupper(phrase[i]);
            atWordStart = 0;
        } else if (phrase[i] == ' ') {
            atWordStart = 1;
        }
    }
    
    result[resultIdx] = '\0';
    return result;
}

int main() {
    char phrase[1000];
    fgets(phrase, sizeof(phrase), stdin);
    phrase[strcspn(phrase, "\n")] = 0;
    
    char* result = solution(phrase);
    printf("%s\n", result);
    return 0;
}

Time & Space Complexity

Time Complexity

⏱️

O(n)

Single pass through all n characters in the phrase

✓ Linear Growth

Space Complexity

O(k)

k is number of words - space for result string

✓ Linear Space

23.4K Views

Medium Frequency

~15 min Avg. Time

892 Likes

Ln 1, Col 1

Smart Actions

💡 Explanation

AI Ready

💡 Suggestion Tab to accept Esc to dismiss

// Output will appear here after running code

Code Editor Closed

Click the red button to reopen

Acronym Generator - Problem

Input & Output

Constraints

Visualization

Related Problems

Common Approaches

Brute Force - Character by Character — Algorithm Steps

Visualization

Code -

Time & Space Complexity

Select Compiler