28. Implement strStr()(easy)

SourDumplings

于 2019-01-17 18:23:39 发布

阅读量137

点赞数

CC 4.0 BY-SA版权

分类专栏： LeetCode刷题练习

本文链接：https://blog.youkuaiyun.com/SourDumplings/article/details/86529228

LeetCode刷题练习专栏收录该内容

111 篇文章

订阅专栏

本文详细介绍了如何在C++和Java中实现strStr()函数，该函数用于查找一个字符串在另一个字符串中的首次出现位置。当目标字符串为空时，将返回0，这与C的strstr()和Java的indexOf()保持一致。

Easy

7241117FavoriteShare

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.

For the purpose of this problem, we will return 0 when needle is an empty string. This is consistent to C's strstr() and Java's indexOf().

C++：

/*
 @Date    : 2019-01-15 20:46:07
 @Author  : 酸饺子 (changzheng300@foxmail.com)
 @Link    : https://github.com/SourDumplings
 @Version : $Id$
*/

/*
https://leetcode.com/problems/implement-strstr/
 */

class Solution
{
public:
    int strStr(string haystack, string needle)
    {
        if (needle.empty())
        {
            return 0;
        }
        return haystack.find(needle);
    }
};

Java：

/**
 * @Date    : 2019-01-15 20:49:24
 * @Author  : 酸饺子 (changzheng300@foxmail.com)
 * @Link    : https://github.com/SourDumplings
 * @Version : $Id$
 *
 * https://leetcode.com/problems/implement-strstr/
*/

class Solution
{
    public int strStr(String haystack, String needle)
    {
        return haystack.indexOf(needle);
    }
}