“This is the 16th day of my participation in the Gwen Challenge in November. Check out the details: The Last Gwen Challenge in 2021.”

KMP

The time complexity of -KMP algorithm is O(m+ N), and the main advantage is that the main string does not backtrace

I. Example diagram

# 2

Analyze the above example

P as mode string 'aabaac's 'as main string' aabaabaac'Copy the code

1. First we solve the next array

2. The main string goes straight ahead, and the mode string is compared

A a b a a b a b a a c a a b a a a a a b a a 'c' Next [6]= next[j]' ② a a b a a b a b a c a a b a a b a a'c' A a b a a B a a B a a C a a b a A A C a A B a A CCopy the code

Method two in the example above

Case 1 figure 

1. First of all, we first work out partial matching values of the prefixes and suffixes of the pattern string, such as' Fig.1 '2. A a B A B a B A A B A A C a A B A A A A B a A 'C' So we see that the fifth digit 'a' matches '2', and the matched digit is '5', so using the formula '5-2=3', we move the pattern string back three places to get ② ② A A B A B A B A A C A B A A 'C' again, same idea, Again, '5-2=3'. Move the pattern string back three places to get ③ ③ a A B a B a A B A A C a B a A A CCopy the code

eggs

  • At this point, let’s go back to example 1, where we want to figure outnextThe array is the one shown in figure 1
  • Match the valueIt goes one to the rightIsn’t it amazing!