A B C A A C B B C B A D A A B C A C B D
原始 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 2 3 4 0 0
优化 -1 0 0 -1 1 1 0 0 0 0 -1 1 -1 1 0 0 -1 4 0 0
Java代码：
public static int[] next(char[] t){
int [] next = new int[t.length];
next[0]=-1;
int i=0,j=-1;
while(i<t.length-1){
if(j==-1||t[i]==t[j]){
i++;
j++;
if(t[i]!=t[j])
next[i]=j;
esle
next[i]=next[j];
}
}
return next;
}