Implement strStr().
Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
|
public class StrStr {
public int strStr(String haystack, String needle) {
if (needle == null || needle.length() == 0) {
return 0;
}
if (haystack == null || haystack.length() == 0) {
return -1;
}
for (int i = 0; i < haystack.length(); i++) {
char c = haystack.charAt(i);
if (haystack.length() - i + 1 < needle.length()) {
return -1;
}
if (c == needle.charAt(0)) {
int j = 0;
int k = i;
for (; j < needle.length() && k < haystack.length(); j++, k++) {
if (needle.charAt(j) != haystack.charAt(k)) {
break;
}
}
if (j == needle.length()) {
return (k - j);
}
}
}
return -1;
}
}
|