【LeetCode】28. Implement strStr()

最新推荐文章于 2021-10-20 10:58:48 发布

YolandaJia

最新推荐文章于 2021-10-20 10:58:48 发布

阅读量163

点赞数

CC 4.0 BY-SA版权

分类专栏： LeetCode

本文链接：https://blog.youkuaiyun.com/YolandaJia/article/details/81560682

LeetCode 专栏收录该内容

35 篇文章

订阅专栏

本文介绍了一个简单的字符串搜索算法实现，该算法用于寻找一个子串(needle)在目标字符串(haystack)中首次出现的位置，并返回该位置的索引。如果子串不存在于目标字符串中，则返回-1。文章通过一个具体的代码示例来展示如何实现这一功能。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

Implement strStr().

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

Example 1:

Input: haystack = "hello", needle = "ll"
Output: 2

Example 2:

Input: haystack = "aaaaa", needle = "bba"
Output: -1

Clarification:

What should we return when needle is an empty string? This is a great question to ask during an interview.

Code:

public int strStr(String haystack, String needle) {
        if (haystack.length() < needle.length()) {
            return -1;
        }
        for (int i = 0; i <= haystack.length() - needle.length(); i++){
            int j = 0;
            while (j < needle.length()){
                if (haystack.charAt(i + j) != needle.charAt(j)) {
                    break;
                }
                j++;
            } 
            if (j == needle.length()){
                return i;
            }
        }
        return -1;
    }