问题描述
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().
解决思路
使用SubString函数，轻松破之。
代码
package leetcode;
public class ImplementstrStr {
public int strStr(String haystack, String needle) {
int len1 = haystack.length();
int len2 = needle.length();
if (len1 < len2) return -1;
if(len2 == 0) return 0;
for (int i = 0; i <= len1 - len2; i++){
if (needle.equals(haystack.substring(i,i+len2))) {
return i;
}
}
return -1;
}
}
