Getting Started with KMP algorithms

Learn a look at the pornography algorithm I think I can get better.

Obviously yesterday's question I all know how to imitate, but still will not change KMP, is I learn ugly

KMP is a linear time string matching algorithm designed by Knuth-morris-pratt three people

An introduction to the NXT array, horizontal slot, direct find too cool

Is that I can fall back when I match, because of the limited ability of the character

For example, Aaaaaaaaab and Aaaab to match, Aaaab is a pattern string, Aaaaaaaaab is a matching string, I do not have to back so many times, because in time to push down on the good

I'm a part of the match and I can go back to a certain position.

Here is a demo

I used to ask for the prefix function

void Pre (char *p) {    int  i,m,j;    M=strlen (p);    nex[0]=nex[1]=0;      for (int i=1; i<m; i++)    {        J=nex[i];          while (J&&p[i]!=p[j]) j=nex[j];        Nex[i+1]=p[i]==p[j]?j+1:0;    }}

Aaaab

0 0 1) 2 3

Aba

0 0 0

Pseudo code

Kmp-matcher (T,P) 1N ←length[T] 2m ←length[P] 3Pi←compute-prefix-function (P) 4Q ←0? Number of characters matched. 5 for I ←1 to N ? Scan the text from left to right. 6 Do While Q > 0 andP[Q+ 1]≠T[I] 7 Do Q ←π[q ] if  p  [q  + 1] = t  [i ] 9 then  q  ←q  + 1 if  q  = m  p  matched?11 then  print "Pattern occurs with Shift" i -m  q  ←π[q ]         

Compute-prefix-function (P) 1m ←length[P] 2Π[1]←0 3k ←0 4 for Q ←2 to  m  5 do whi Le  k  > 0 and p  [k  + 1] ≠p  [q ] 6 do  k  ←π[k ] 7 if  p  [k  + 1] = EM class= "emphasis" >p  [q ] 8 then   K  ←k  + 1 9 π[q  ] ←k  return  π         

Getting started with the KMP algorithm