Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
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().
判断needle字符串是否在haystack中,如果在,就返回下标,不在就返回-1
public int strStr(String haystack, String needle) {
if(needle.length() < 1) return 0;
if(haystack.equals(needle)) return 0;
for (int i = 0; i <= haystack.length()-needle.length(); i++) {
if(haystack.charAt(i)==needle.charAt(0)){
if(needle.equals(haystack.substring(i, i+needle.length()))){
return i;
}
}
}
return -1;
}