Easy String

Yelp

2020-05-23

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

Question:

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.

Solution:

Using the startsWith method from the string. Otherwise, it can also be solved by using the substring and .equals() method.

Using startsWith:

class Solution {
    public int isPrefixOfWord(String sentence, String searchWord) {
        int counter = 1;
        for(String s: sentence.split(" ")) {
            if (s.startsWith(searchWord)) {
                return counter;
            }
            counter++;
        }
        return -1;
    }
}

Using substring and .equals() method:

class Solution {
    public int isPrefixOfWord(String sentence, String searchWord) {
        int counter = 1;
        for(String s: sentence.split(" ")) {
            if (s.length() >= searchWord.length() && s.substring(0, searchWord.length()).equals(searchWord)) {
                return counter;
            }
            counter++;
        }
        return -1;
    }
}