顺序遍历字符串，双指针技巧，用 startsWith (javascript / typescript / java) / StartsWith (c#) / startswith (python) / str_starts_with (php) / strings.HasPrefix (golang) 接口，求解《1455. 检查单词是否为句中其他单词的前缀》
例题
1455. 检查单词是否为句中其他单词的前缀
给你一个字符串 sentence 作为句子并指定检索词为 searchWord ，其中句子由若干用 单个空格 分隔的单词组成。请你检查检索词 searchWord 是否为句子 sentence 中任意单词的前缀。
如果 searchWord 是某一个单词的前缀，则返回句子 sentence 中该单词所对应的下标（下标从 1 开始）。如果 searchWord 是多个单词的前缀，则返回匹配的第一个单词的下标（最小下标）。如果 searchWord 不是任何单词的前缀，则返回 -1 。
字符串 s 的 前缀 是 s 的任何前导连续子字符串。
示例 1：
输入：sentence = "i love eating burger", searchWord = "burg"
输出：4
解释："burg" 是 "burger" 的前缀，而 "burger" 是句子中第 4 个单词。
示例 2：
输入：sentence = "this problem is an easy problem", searchWord = "pro"
输出：2
解释："pro" 是 "problem" 的前缀，而 "problem" 是句子中第 2 个也是第 6 个单词，但是应该返回最小下标 2 。
示例 3：
输入：sentence = "i am tired", searchWord = "you"
输出：-1
解释："you" 不是句子中任何单词的前缀。
提示：
1 <= sentence.length <= 100
1 <= searchWord.length <= 10
sentence 由小写英文字母和空格组成。
searchWord 由小写英文字母组成。
答案
顺序遍历 · startsWith / StartsWith (c#) / startswith (python) / str_starts_with (php) / strings.HasPrefix (golang)
var isPrefixOfWord = function(sentence, searchWord) {
const a = sentence.split(' ')
for (let i = 0; i < a.length; i++) {
if (a[i].startsWith(searchWord)) return i + 1
}
return -1
};var isPrefixOfWord = function(sentence, searchWord) { // findIndex
return sentence.split(' ').findIndex(v => v.startsWith(searchWord)) + 1 || -1
};function isPrefixOfWord(sentence: string, searchWord: string): number {
const a = sentence.split(' ')
for (let i = 0; i < a.length; i++) {
if (a[i].startsWith(searchWord)) return i + 1
}
return -1
};function isPrefixOfWord(sentence: string, searchWord: string): number {
return sentence.split(' ').findIndex(v => v.startsWith(searchWord)) + 1 || -1
};class Solution {
public int isPrefixOfWord(String sentence, String searchWord) {
String[] a = sentence.split(" ");
for (int i = 0; i < a.length; i++) {
if (a[i].startsWith(searchWord)) return i + 1;
}
return -1;
}
}public class Solution {
public int IsPrefixOfWord(string sentence, string searchWord) {
string[] a = sentence.Split(" ");
for (int i = 0; i < a.Length; i++) {
if (a[i].StartsWith(searchWord)) return i + 1;
}
return -1;
}
}class Solution:
def isPrefixOfWord(self, sentence: str, searchWord: str) -> int:
for i, s in enumerate(sentence.split(' ')):
if s.startswith(searchWord): return i + 1
return -1class Solution {
function isPrefixOfWord($sentence, $searchWord) {
foreach (explode(' ', $sentence) as $i => $s) {
if (str_starts_with($s, $searchWord)) return $i + 1;
}
return -1;
}
}func isPrefixOfWord(sentence string, searchWord string) int {
for i, s := range strings.Split(sentence, " ") {
if strings.HasPrefix(s, searchWord) {
return i + 1
}
}
return -1
}顺序遍历 · 双指针
function isPrefixOfWord(sentence: string, searchWord: string): number {
let index = 0
const n = sentence.length, m = searchWord.length
for (let i = 0; i < n; i++) {
let start = i
while (i < n && sentence[i] !== ' ') i++
index++
let j = 0
while (start + j < n && j < m && sentence[start + j] === searchWord[j]) j++
if (j === m) return index
}
return -1
};class Solution {
function isPrefixOfWord($sentence, $searchWord) {
$n = strlen($sentence);
$m = strlen($searchWord);
$index = 0;
for ($i = 0; $i < $n; $i++) {
$start = $i;
while ($i < $n && $sentence[$i] !== ' ') $i++;
$index++;
$j = 0;
while ($start + $j < $n && $j < $m && $sentence[$start + $j] === $searchWord[$j]) $j++;
if ($j === $m) return $index;
}
return -1;
}
}func isPrefixOfWord(sentence string, searchWord string) int {
n, m, index := len(sentence), len(searchWord), 0
for i := 0; i < n; i++ {
start := i
for i < n && sentence[i] != ' ' {
i++
}
index++
j := 0
for start + j < n && j < m && sentence[start + j] == searchWord[j] {
j++
}
if j == m {
return index
}
}
return -1
}class Solution {
public int isPrefixOfWord(String sentence, String searchWord) {
int n = sentence.length(), m = searchWord.length(), index = 0;
for (int i = 0; i < n; i++) {
int start = i;
while (i < n && sentence.charAt(i) != ' ') i++;
index++;
int j = 0;
while (start + j < n && j < m && sentence.charAt(start + j) == searchWord.charAt(j)) j++;
if (j == m) return index;
}
return -1;
}
}public class Solution {
public int IsPrefixOfWord(string sentence, string searchWord) {
int n = sentence.Length, m = searchWord.Length, index = 0;
for (int i = 0; i < n; i++) {
int start = i;
while (i < n && sentence[i] != ' ') i++;
index++;
int j = 0;
while (start + j < n && j < m && sentence[start + j] == searchWord[j]) j++;
if (j == m) return index;
}
return -1;
}
}int isPrefixOfWord(char * sentence, char * searchWord){
int n = strlen(sentence), m = strlen(searchWord), index = 0;
for (int i = 0; i < n; i++) {
int start = i;
while (i < n && sentence[i] != ' ') i++;
index++;
int j = 0;
while (start + j < n && j < m && sentence[start + j] == searchWord[j]) j++;
if (j == m) return index;
}
return -1;
}class Solution {
public:
int isPrefixOfWord(string sentence, string searchWord) {
int n = sentence.size(), m = searchWord.size(), index = 0;
for (int i = 0; i < n; i++) {
int start = i;
while (i < n && sentence[i] != ' ') i++;
index++;
int j = 0;
while (start + j < n && j < m && sentence[start + j] == searchWord[j]) j++;
if (j == m) return index;
}
return -1;
}
};class Solution:
def isPrefixOfWord(self, sentence: str, searchWord: str) -> int:
n, m, index, i = len(sentence), len(searchWord), 0, 0
while i < n:
start = i
while i < n and sentence[i] != ' ': i += 1
index, i, j = index + 1, i + 1, 0
while start + j < n and j < m and sentence[start + j] == searchWord[j]: j += 1
if j == m: return index
return -1