LeetCode Implement strStr()
Implement strStr().
Returns a pointer to the first occurrence of needle in haystack, or null if needle is not part of haystack.
1 public class Solution { 2 public String strStr(String haystack, String needle) { 3 if (haystack.equals(needle)) { 4 return haystack; 5 } 6 int haylen=haystack.length(); 7 int neelen=needle.length(); 8 if (neelen>haylen) { 9 return null; 10 } 11 12 int i,j=0; 13 int phay=0; 14 while (phay<haylen-neelen) { 15 i=phay; 16 j=0; 17 while (j<neelen && i<haylen && needle.charAt(j)==haystack.charAt(i)) { 18 ++j; 19 ++i; 20 } 21 if (j==neelen) { 22 return haystack.substring(phay); 23 } 24 ++phay; 25 26 } 27 return null; 28 } 29 }