5416. Check If a Word Occurs As a Prefix of Any Word in a Sentence

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.

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给定一个句子和一个待搜索词，问该搜索词是否可能是这个句子中某个词的前缀。

直接暴力搜索即可，因为指定必须是前缀，所以其实直接截取相同长度的前缀判断相等即可。

class Solution {
public:
	int isPrefixOfWord(string sentence, string searchWord) {
		int idx = 1, i = 0, j = 0, n = sentence.size();
		while (i < n) {
			j = i + 1;
			while (j < n&&sentence[j] != ' ')++j;
			string cur = sentence.substr(i, j - i);
			size_t pos = cur.find(searchWord);
			if (pos != string::npos&&pos == 0) {
				return idx;
			}
			++idx;
			i = j + 1;
		}
		return -1;
	}
};

本代码提交AC。