Last active
April 5, 2020 20:42
-
-
Save vickonrails/8cb697acd6287e7b6a3c6084bae21f1f to your computer and use it in GitHub Desktop.
Implementation of Knuth-Morris-Pratt string search algorithm in JavaScript
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
// See notes at vickon.netlify.com/notes/algorithms-and-data-structures-day-3 | |
let = longestPrefixSuffix => { | |
let table = new Array(pattern.length) | |
let pointer = 0 | |
table[0] = 0 | |
for (let i = 1; i < pattern.length; i++) { | |
while (pointer > 0 && pattern.charAt(i) !== pattern.charAt(pointer)) { | |
pointer = table[pointer - 1] | |
} | |
if (pattern.charAt(i) === pattern.charAt(pointer)) { | |
pointer++ | |
} | |
table[i] = pointer | |
} | |
return table | |
} | |
let match = (text, pattern) => { | |
let prefixes = longestPrefixSuffix(pattern), | |
matches = [] | |
let j = 0, | |
i = 0 | |
while (i < text.length) { | |
if (text.charAt(i) === pattern.charAt(j)) { | |
i++ | |
j++ | |
} | |
if (j === pattern.length) { | |
matches.push(i - j) | |
j = prefixes[j - 1] | |
} else if (text.charAt(i) !== pattern.charAt(j)) { | |
if (j !== 0) { | |
j = prefixes[j - 1] | |
} else { | |
i++ | |
} | |
} | |
} | |
return matches | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment