KMP_java实现

package test;public class KMP {public int[] getNext(String p) {if(p == null || p.length() == 0)return null;int[] next = new int[p.length()];int i = 0;int j = -1;next[0] = -1;while(i < p.length() - 1) {if(j == -1 || p.charAt(i) == p.charAt(j)) {i++;j++;if(p.charAt(i) == p.charAt(j))next[i] = next[j];elsenext[i] = j;} else {j = next[j];}}return next;}public int KMP1(String s, String p) {if(s == null || p == null)return -1;int[] next = getNext(p);int res = -1;int i = 0;int j = 0;while(i < s.length()) {if(j == -1 || s.charAt(i) == p.charAt(j)) {i++;j++;} else {j = next[j];}if(j == p.length()) {res = i - p.length();break;}}return res;}public static void main(String[] arg) {KMP kmp = new KMP();System.out.println(kmp.KMP1("abcd", "abcdef"));}}