Coding problem · Easy · Basics

Longest Word in a Sentence

Easy Algorithms & data structures

Given a sentence s of words separated by single spaces, return the longest word. If several words share the maximum length, return the first of them.

Example 1

Input: s = "I love programming puzzles"
Output: "programming"

Example 2

Input: s = "cat dog"
Output: "cat"
Explanation: Both have 3 letters; cat comes first.

Hints

Hint 1

Keep track of the best word so far while you loop.

Hint 2

Only replace it when a word is strictly longer, so ties keep the earlier word.

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Solution and explanation

Show the solution

Time O(n) · Space O(n)

One pass over the words: if the current word is longer than the best so far, it becomes the best. Using > (not >=) keeps the first of equally long words.

Reference solution

function longestWord(s) {
  let best = '';
  for (const w of s.split(' ')) if (w.length > best.length) best = w;
  return best;
}

function longestWord(s: string): string {
  let best = '';
  for (const w of s.split(' ')) if (w.length > best.length) best = w;
  return best;
}

def longest_word(s: str) -> str:
    best = ''
    for w in s.split(' '):
        if len(w) > len(best):
            best = w
    return best

<?php

function longestWord(string $s): string
{
    $best = '';
    foreach (explode(' ', $s) as $w) {
        if (strlen($w) > strlen($best)) {
            $best = $w;
        }
    }
    return $best;
}

class Solution {
    public String longestWord(String s) {
        String best = "";
        for (String w : s.split(" ")) if (w.length() > best.length()) best = w;
        return best;
    }
}

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