1455. Check If a Word Occurs As a Prefix of Any Word in a Sentence #

Problem #

Given a sentence that consists of some words separated by a single space, and a searchWord.

You have to check if searchWord is a prefix of any word in sentence.

Return the index of the word in sentence where searchWord is a prefix of this word (1-indexed).

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.

Example 4:

Input: sentence = "i use triple pillow", searchWord = "pill"
Output: 4

Example 5:

Input: sentence = "hello from the other side", searchWord = "they"
Output: -1

Constraints:

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

Problem Summary #

Given a string sentence as a sentence and a search term searchWord, where the sentence consists of several words separated by a single space. Check whether the search term searchWord is a prefix of any word in the sentence sentence.

• If searchWord is the prefix of a word, return the corresponding index of that word in the sentence sentence (indices start from 1).
• If searchWord is the prefix of multiple words, return the index of the first matched word (minimum index).
• If searchWord is not the prefix of any word, return -1.

The “prefix” of a string S is any leading contiguous substring of S.

Solution Approach #

• Given 2 strings, one is the matching string, and the other is the sentence. Find the word in the sentence that has the matching string as a prefix, and return the index of the first matched word.
• Easy problem. According to the problem statement, scan the sentence once and match along the way.

Code #

package leetcode

import "strings"

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