KMP算法Java实现

public class KMP {

public static int[] next(char[] s)

{

int length = s.length;

int next[]=new int[length];

next[0]=-1;

next[1]=0;

for(int i=2;i<length;i++)

{

/*如果当前所求的数的前一位和他的next［］位相等的话，那么当前所求的位的next数就是它的前一位的next［］再加1*/

int temp = next[i-1];

while(temp!=-1&&s[i-1]!=s[temp])

{

temp = next[temp];

}

if(temp==-1) next[i] = 0;

else next[i] = temp+1;

}

return next;

}

public static int compare(char[] t, char[] s)

{

int tlen = t.length;

int slen = s.length;

int [] next = next(s);

int i,j;

for(i=0,j=0;i<tlen-slen&&j<slen;)

{

if(t[i]==s[j]){

i++;j++;

}else{

j=next[j];

if(j==-1)

{

i++;j++;

}

}

}

if(j<slen) return -1;

else return i;

}

/**

* @param args

*/

public static void main(String[] args) {

// TODO Auto-generated method stub

char s[] = "abab".toCharArray();

char t[] = "zhangabliababling".toCharArray();

int temp = compare(t,s);

System.out.println(temp);

}

}