LeetCode 1455. Check If a Word Occurs As a Prefix of Any Word in a Sentence Solution in Java, C++, Python & More | Explanation + Code

Description

Given a sentence that consists of some words separated by a single space, and a searchWord, check if searchWord is a prefix of any word in sentence.

Return the index of the word in sentence (1-indexed) where searchWord is a prefix of this word. If searchWord is a prefix of more than one word, return the index of the first word (minimum index). If there is no such word return -1.

A prefix of a string s is any leading contiguous substring of s.

 

Example 1:

Input: sentence = "i love eating burger", searchWord = "burg"
Output: 4
Explanation: "burg" is prefix of "burger" which is the 4th word in the sentence.

Example 2:

Input: sentence = "this problem is an easy problem", searchWord = "pro"
Output: 2
Explanation: "pro" is prefix of "problem" which is the 2nd and the 6th word in the sentence, but we return 2 as it's the minimal index.

Example 3:

Input: sentence = "i am tired", searchWord = "you"
Output: -1
Explanation: "you" is not a prefix of any word in the sentence.

 

Constraints:

• 1 <= sentence.length <= 100
• 1 <= searchWord.length <= 10
• sentence consists of lowercase English letters and spaces.
• searchWord consists of lowercase English letters.

Solutions

Solution 1: String Splitting

We split sentence by spaces into words, then iterate through words to check if words[i] is a prefix of searchWord. If it is, we return i+1. If the iteration completes and no words satisfy the condition, we return -1.

The time complexity is O(m × n), and the space complexity is O(m). Here, m and n are the lengths of sentence and searchWord, respectively.

PythonJavaC++GoTypeScriptRustPHP

class Solution: def isPrefixOfWord(self, sentence: str, searchWord: str) -> int: for i, s in enumerate(sentence.split(), 1): if s.startswith(searchWord): return i return -1(code-box)

class Solution { public int isPrefixOfWord(String sentence, String searchWord) { String[] words = sentence.split(" "); for (int i = 0; i < words.length; ++i) { if (words[i].startsWith(searchWord)) { return i + 1; } } return -1; } }(code-box)

class Solution { public: int isPrefixOfWord(string sentence, string searchWord) { stringstream ss(sentence); string s; for (int i = 1; ss >> s; ++i) { if (s.find(searchWord) == 0) { return i; } } return -1; } };(code-box)

func isPrefixOfWord(sentence string, searchWord string) int { for i, s := range strings.Split(sentence, " ") { if strings.HasPrefix(s, searchWord) { return i + 1 } } return -1 }(code-box)

function isPrefixOfWord(sentence: string, searchWord: string): number { const ss = sentence.split(/\s/); const n = ss.length; for (let i = 0; i < n; i++) { if (ss[i].startsWith(searchWord)) { return i + 1; } } return -1; }(code-box)

impl Solution { pub fn is_prefix_of_word(sentence: String, search_word: String) -> i32 { let ss = sentence.split_whitespace().collect::<Vec<&str>>(); for i in 0..ss.len() { if ss[i].starts_with(&search_word) { return (i + 1) as i32; } } -1 } }(code-box)

class Solution { /** * @param String $sentence * @param String $searchWord * @return Integer */ function isPrefixOfWord($sentence, $searchWord) { $words = explode(' ', $sentence); for ($i = 0; $i < count($words); ++$i) { if (strpos($words[$i], $searchWord) === 0) { return $i + 1; } } return -1; } }(code-box)