KMP algorithm Java version __ algorithm

1 Principle

Refer to the section 5.7 of the 5th chapter of the "Liar data Structure": KMP Pattern matching algorithm

2 Java Code

Kmp.java

Package Leaning.string.KMP; public class KMP {public static int indexkmp (string source, String Target,int pos) {/* I is used for subscript values at the current position of the main string source, if the POS is not 
		
		1 from POS position start to match/int i = pos;
		
		/* j for substring Target in the current position subscript/Int J = 1;  
		
		/* Define a set of next array */int[] next = new Int[intarraylength.length];
		
		/* Target is parsed to get next array */next = Nextutil.getnext (target);
		Converts a source,target string into a character array char[] Sourcechar = Kmpstringutil.stringtochar (source);
		
		char[] Targetchar = Kmpstringutil.stringtochar (target); If I is less than the source length and target is less than the target length, execute the loop while (I <=source.length () && J <= Target.length ()) {if j==0 | | s
				Ourcechar[i] = = Targetchar[j]) {++i;
			++j;
			}else{j = Next[j];
		} if (J > Target.length ()) {return i-target.length ();	
		}else{return 0;
		} public static void Main (string args[]) {string source = ' ASDKFJSLKFJWEJDKLFJEW8ODKLFJSDLKFJSLKDJ ';
		String target = "W8odkl";
		int pos = 0; int p = kmp.indexkmP (source, target, POS);
	System.out.println ("in position" +p + "exact Match");
 }
}

Nextutil.java

Package Leaning.string.KMP;

public class Nextutil {
	
	/**
	 * * 
	 gets next array 
	 *
	/public static int[] GetNext (String targetstr) {
       if (targetstr==null) return null;
       char[] targetmodify = Kmpstringutil.stringtochar (TARGETSTR); Change Targetstr string to character array
       int length = Targetstr.length ();
       Get next array
       int i,j;
       i = 1;
       j = 0;
       int next[] = new Int[intarraylength.length];
       while (I < length) {
    	   if (j = = 0 | | targetmodify[i] = = Targetmodify[j]) {//targetmodify[i] denotes suffix single character, targetmodify[j] table A single character ++i that shows a prefix 
    		   ;
    		   ++j;
    		   Next[i] = j;
    	   } else{
    		   j = next[j];//If the characters are different, J makes a backtracking} and return
       
	   next;  

	public static void Main (string args[]) {
		string targetstr = "Ababaaaba";
		int next[] = Nextutil.getnext (TARGETSTR);
		for (int i = 0; i < next.length i++) {
			System.out.print (Next[i] + "");}
		}

Intarraylength.java

Package Leaning.string.KMP;

Public  class Intarraylength {
   public  static int length = 255;
}

Kmpstringutil.java

Package Leaning.string.KMP;

The public class Kmpstringutil {public
   
	static char[] Stringtochar (String source) {
		 
	       /**
	        * is transforming source. Make its first digit a placeholder
	        *    Source =    a b c d e F g h
	        * targetmodify = ' A b c d e F g h 
	        * 
	        * * * * * * *
	       char[ ] Targetmodify = new Char[source.length () +1];
	       int length = Source.length (); 
	       for (int i = 0; i < source.length (); i++) {
	    	   targetmodify[i+1] = Source.charat (i);
	       }
		Return targetmodify
	} 
	
}

3 Running Results

Run Kmp.java get the following results