模式匹配之Kmp算法

Kmp:

算法定义借鉴wikipedia:

http://en.wikipedia.org/wiki/Knuth%E2%80%93Morris%E2%80%93Pratt_algorithm#KMP_algorithm

代码:

import java.util.Scanner;

public class Main {

	public static void main(String[] argv){

		Main u = new Main();
Scanner in = new Scanner(System.in);
String t = in.nextLine();
String s = in.nextLine();
int[] next = new int[s.length()];
char [] n = t.toCharArray();
char [] m = s.toCharArray();
next = u.check(m);
for(int i=0; i<next.length; i++){
System.out.print(next[i]);
}
System.out.println();
int k=0; int num=0;
for(int i=0; i<t.length();i++){ if(n[i]==m[k])
{
k++;
if(k==m.length)
{num++;k=next[k-1];}
}
else
k=next[k];
}
System.out.println(num); } public int[] check(char [] t){ int next[] = new int [t.length];
next[0]=0;
int j=1;
while(j<t.length){
int k=next[j-1];
while (t[j]!=t[k]&&k!=0)
k=next[k-1];
if(t[j]==t[k])
next[j]=k+1;
else
next[j]=0;
// System.out.println(" "+next[j]);
j++;
}
return next;
}
}

  运行效果:

模式匹配之Kmp算法

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