1455. Check If A Word Occurs As A Prefix Of Any Word In A Sentence¶

Intuition¶

This problem can be solved by splitting the sentence into words, iterating through each word to check if the given searchWord is a prefix, and returning the index of the first occurrence where this is true.

Approach¶

Splitting the Sentence:¶

Use strings.Fields(sentence) to split the input sentence into words.

Iterating Through Words:¶

Use strings.HasPrefix(word, searchWord) to check if the searchWord is a prefix of the current word.

Indexing:¶

Return the 1-indexed position (i + 1) of the first word where searchWord is a prefix.
If no such word exists, return -1.

Complexity¶

Time Complexity: O(n · m) where:
n is the number of words in the sentence.
m is the average length of words in the sentence.
Space Complexity: O(n) where:
Splitting the sentence into words requires O(n) additional space.

Code¶

Go¶

import "strings"

func isPrefixOfWord(sentence string, searchWord string) int {
    words := strings.Fields(sentence)
    for index, word := range words {
        if strings.HasPrefix(word, searchWord) {
            return index + 1
        }
    }
    return -1
}

Java¶

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