Longest Word Finder - Problem

Given a sentence as a string, find and return the longest word in the sentence.

If there are multiple words with the same maximum length, return the first occurrence.

Note: Words are separated by spaces, and you can assume the input contains only alphabetic characters and spaces.

Input & Output

Example 1 — Basic Case

$ Input: sentence = "The quick brown fox jumps"

› Output: "brown"

💡 Note: Words are ["The"(3), "quick"(5), "brown"(5), "fox"(3), "jumps"(5)]. Maximum length is 5. First word with length 5 is "brown".

Example 2 — Single Word

$ Input: sentence = "Hello"

› Output: "Hello"

💡 Note: Only one word exists, so "Hello" is the longest word.

Example 3 — All Equal Length

$ Input: sentence = "cat dog pig"

› Output: "cat"

💡 Note: All words have length 3. Return first occurrence "cat".

Constraints

1 ≤ sentence.length ≤ 10⁴
sentence contains only lowercase and uppercase English letters and spaces
sentence does not start or end with a space

Visualization

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Asked in

G Google 25 M Microsoft 18 a Amazon 22

The key insight is to process the sentence efficiently while tracking the longest word. The optimal approach uses a single pass without creating extra arrays. Time: O(n), Space: O(1).

Common Approaches

✓ Single Pass Without Split

⏱️ Time: O(n) Space: O(1)

Traverse the sentence once, tracking current word length and the longest word found so far. When encountering a space, compare current word length with maximum and update if needed.

Split and Compare All

⏱️ Time: O(n) Space: O(n)

Split the sentence by spaces to get individual words, then iterate through all words to find the one with maximum length. Return the first word that has the maximum length.

Single Pass Without Split — Algorithm Steps

Step 1: Initialize variables for current word, longest word, and lengths
Step 2: Iterate through each character in the sentence
Step 3: Build current word; on space, compare lengths and update longest
Step 4: Handle last word after loop ends

Visualization

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Step-by-Step Walkthrough

Character Scan

Process each character, building current word

Space Detection

On space, compare current word with longest

Final Result

Return the longest word found

Code -

solution.c — C

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

char* solution(char* sentence) {
    static char longestWord[1000];
    char currentWord[1000];
    int maxLength = 0;
    int currentLength = 0;
    longestWord[0] = '\0';
    currentWord[0] = '\0';
    
    for (int i = 0; sentence[i] != '\0'; i++) {
        char ch = sentence[i];
        if (ch == ' ') {
            currentWord[currentLength] = '\0';
            if (currentLength > maxLength) {
                maxLength = currentLength;
                strcpy(longestWord, currentWord);
            }
            currentLength = 0;
        } else {
            currentWord[currentLength++] = ch;
        }
    }
    
    // Handle last word
    currentWord[currentLength] = '\0';
    if (currentLength > maxLength) {
        strcpy(longestWord, currentWord);
    }
    
    return longestWord;
}

int main() {
    char sentence[10000];
    fgets(sentence, sizeof(sentence), stdin);
    sentence[strcspn(sentence, "\n")] = 0;
    
    char* result = solution(sentence);
    printf("%s\n", result);
    return 0;
}

Time & Space Complexity

Time Complexity

⏱️

O(n)

Single pass through all characters in the sentence

✓ Linear Growth

Space Complexity

O(1)

Only uses variables to track current and longest words, no extra arrays

⚡ Linearithmic Space

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Longest Word Finder - Problem

Input & Output

Constraints

Visualization

Related Problems

Common Approaches

Single Pass Without Split — Algorithm Steps

Visualization

Code -

Time & Space Complexity

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