Leetcode: Implement strStr()

最新推荐文章于 2022-01-16 15:00:19 发布

LuckySeven7777

最新推荐文章于 2022-01-16 15:00:19 发布

阅读量517

点赞数

CC 4.0 BY-SA版权

分类专栏： Java学习

本文链接：https://blog.youkuaiyun.com/LuckySeven7777/article/details/43882301

Java学习专栏收录该内容

33 篇文章

订阅专栏

本文详细介绍了如何实现字符串查找算法strStr，用于在给定的字符串中查找指定子串的第一个出现位置，并返回该位置索引，若不存在则返回-1。包括更新后的函数签名解析及代码实现。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

Problem:

Implement strStr().

Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

Update (2014-11-02):
The signature of the function had been updated to return the index instead of the pointer. If you still see your function signature returns a char * or String, please click the reload button to reset your code definition.

Solution:

Code:

public class Solution {
    public int strStr(String haystack, String needle) {
    if (needle == null || needle.length() == 0) return 0;
    for (int i = 0; i < haystack.length() - needle.length() + 1; i++) {
        int j = 0;
        int start = i;
        while(haystack.charAt(i) == needle.charAt(j)) {
            j++;
            i++;
            if (j == needle.length()) return start;
        }
        i = start;
    }
    return -1;
    }
}