AC Automaton---fail pointer

Let's see how the Trie tree is constructed before you see it.

The words on the tree are (from top to bottom)

{He, hers, his, she}

Divided into 3 layers as shown in the figure

See the third floor

It's "she."

which

①s point to Root

②h first find the fail pointer of S, found to be the number NO. 0 pointer, not h,

Then H is not happy, then ask s the fail pointer root: "You have no son and I named H."

Root says: "Yes, you point to him."

Then H was pleased to point to the first line of H.

③e began to look, first asked his father H: "Your fail pointer pointing to who"

H said, "The first line on the chart, the H ah."

Then E went to the top of the line and asked, "Do you have a son like me?"

On the first line of the picture, the H said, "Yes, he's the address xxx."

The last e's fail pointer points to the XXX address, which is the first line of the E.

found that, if a string to find the third line after the E character characters mismatch, it means that he should have a ' he ' in front

The failed pointer to just e points to the E of the first line of ' he ... '.

This saves time by not having to look for it again from H, but then the first line of E to continue looking backwards.

AC Automaton---fail pointer