KMP algorithm Java implementation strategy mode __ algorithm

KMP algorithm is a classic algorithm, online many great gods have given a very detailed description, this no longer repeat.

The following is the implementation of the KMP algorithm, which uses a policy pattern.

Public interface Inextbuilder {public
	abstract int[] Build (char[] p);

Implementation of recursive thought of writing Inextbuilder interface

Package COM.SOFT.KMP;

public class Recurnextbuilder implements Inextbuilder  {
	@Override public
	int[] Build (char[] p) {
		int[] Next=new Int[p.length];
		int k=-1;
		Next[0]=-1;
		Traversal 0->p.length-1 for
		(int i=0;i<p.length-1;i++) {
			if k==-1| | P[i]==p[k]) {
				k++;
				next[i+1]=k;
			} else{
				k=next[k];
			}
		return next;
	}

Non-recursive implementation of writing Inextbuilder interface

Package COM.SOFT.KMP;

public class Straitnextbuilder implements Inextbuilder {

	@Override public
	int[] Build (char[) p) {
		// Do it yourself, measure your level return
		null;
	}

Finally, write KMP class and test

Package COM.SOFT.KMP;

public class KMP {
	private inextbuilder nextbuilder;
	Public KMP (Inextbuilder nextbuilder) {
		this.nextbuilder=nextbuilder;
	}
        Public KMP () {
		this.nextbuilder=new recurnextbuilder ();
	}
	public int Kmpmatch (String s,string p) {
		char[] Pa=p.tochararray ();
		Char[] Sa=s.tochararray ();
    	Int[] Next=this.nextbuilder.build (PA);
    	for (int i=0,j=0;i<sa.length;) {
    	     if (J==-1 | | Sa[i]==pa[j]) {
    	    	 i++;j++;
    	     } else{
    	    	 j=next[j];
    	     }
    	     if (j==pa.length) {return
    	    	 i-j
    	     }}
    	return-1; 
    }
    public static void Main (string[] args) {
    	KMP kmp=new KMP ();
    	System.out.println (KMP. Kmpmatch ("Helllo", "Llo"));
    	
	}

Run Result: 3