Java [leetcode 28]Implement strStr()

標籤：

題目描述：

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.

解題思路：

從開頭開始，逐個匹配。

注意特殊情況。

代碼如下：

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

 

Java [leetcode 28]Implement strStr()