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Boyer moore algorithm for pattern searching

Here given code implementation process.

// Java program for
// Boyer moore algorithm for pattern searching
public class Matching
{
	public void findPattern(String text, String pattern)
	{
		// Get the length of given text
		int n = text.length();
		// Get the length of given pattern
		int m = pattern.length();
		// Possible character
		int badchar[] = new int[256];
		// Set initial frequency
		for (int i = 0; i < 256; ++i)
		{
			badchar[i] = -1;
		}
		// Set pattern character position
		for (int i = 0; i < m; ++i)
		{
			badchar[pattern.charAt(i)] = i;
		}
		int j = m - 1;
		int s = 0;
		while (s <= (n - m))
		{
			while (j >= 0 && 
                   pattern.charAt(j) == text.charAt(s + j))
			{
				j--;
			}
			if (j < 0)
			{
				System.out.println("Pattern found at index " + (s));
				if (s + m < n)
				{
					s += m - badchar[text.charAt(s + m)];
				}
				else
				{
					s += 1;
				}
			}
			else
			{
				s += Math.max(1, j - badchar[text.charAt(s + j)]);
			}
			// Rest the value of j
			j = m - 1;
		}
	}
	public static void main(String[] args)
	{
		Matching task = new Matching();
		// Given text
		String text = "LXYZHEQXYZXYZQQHE11HXYZ1E";
		// Search pattern
		String pattern = "XYZ";
		// Find pattern which occurs in given text
		/*
		    Text = LXYZHEQXYZXYZQQHE11HXYZ1E
		    Pattern = XYZ
		    --------------------------------
		    ➀  LXYZHEQXYZXYZQQHE11HXYZ1E
		        ---
		    ➁  LXYZHEQXYZXYZQQHE11HXYZ1E 
		              ---
		    ➂  LXYZHEQXYZXYZQQHE11HXYZ1E 
		                 ---
		    ➃  LXYZHEQXYZXYZQQHE11HXYZ1E 
		                            ---
		*/
		task.findPattern(text, pattern);
	}
}

Output

Pattern found at index 1
Pattern found at index 7
Pattern found at index 10
Pattern found at index 20
// Include header file
#include <iostream>
#include <string>
#include <math.h>

using namespace std;
// C++ program for
// Boyer moore algorithm for pattern searching
class Matching
{
	public: void findPattern(string text, string pattern)
	{
		// Get the length of given text
		int n = text.length();
		// Get the length of given pattern
		int m = pattern.length();
		// Possible character
		int badchar[256];
		// Set initial frequency
		for (int i = 0; i < 256; ++i)
		{
			badchar[i] = -1;
		}
		// Set pattern character position
		for (int i = 0; i < m; ++i)
		{
			badchar[pattern[i]] = i;
		}
		int j = m - 1;
		int s = 0;
		while (s <= (n - m))
		{
			while (j >= 0 && pattern[j] == text[s + j])
			{
				j--;
			}
			if (j < 0)
			{
				cout << "Pattern found at index " 
              		 << s << endl;
				if (s + m < n)
				{
					s += m - badchar[text[s + m]];
				}
				else
				{
					s += 1;
				}
			}
			else
			{
				s += max(1, j - badchar[text[s + j]]);
			}
			// Rest the value of j
			j = m - 1;
		}
	}
};
int main()
{
	Matching *task = new Matching();
	// Given text
	string text = "LXYZHEQXYZXYZQQHE11HXYZ1E";
	// Search pattern
	string pattern = "XYZ";
	// Find pattern which occurs in given text
	/*
	    Text = LXYZHEQXYZXYZQQHE11HXYZ1E
	    Pattern = XYZ
	    --------------------------------
	    ➀  LXYZHEQXYZXYZQQHE11HXYZ1E
	        ---
	    ➁  LXYZHEQXYZXYZQQHE11HXYZ1E 
	              ---
	    ➂  LXYZHEQXYZXYZQQHE11HXYZ1E 
	                 ---
	    ➃  LXYZHEQXYZXYZQQHE11HXYZ1E 
	                            ---
	*/
	task->findPattern(text, pattern);
	return 0;
}

Output

Pattern found at index 1
Pattern found at index 7
Pattern found at index 10
Pattern found at index 20
// Include namespace system
using System;
// Csharp program for
// Boyer moore algorithm for pattern searching
public class Matching
{
	public void findPattern(String text, String pattern)
	{
		// Get the length of given text
		int n = text.Length;
		// Get the length of given pattern
		int m = pattern.Length;
		// Possible character
		int[] badchar = new int[256];
		// Set initial frequency
		for (int i = 0; i < 256; ++i)
		{
			badchar[i] = -1;
		}
		// Set pattern character position
		for (int i = 0; i < m; ++i)
		{
			badchar[pattern[i]] = i;
		}
		int j = m - 1;
		int s = 0;
		while (s <= (n - m))
		{
			while (j >= 0 && pattern[j] == text[s + j])
			{
				j--;
			}
			if (j < 0)
			{
				Console.WriteLine("Pattern found at index " + s);
				if (s + m < n)
				{
					s += m - badchar[text[s + m]];
				}
				else
				{
					s += 1;
				}
			}
			else
			{
				s += Math.Max(1, j - badchar[text[s + j]]);
			}
			// Rest the value of j
			j = m - 1;
		}
	}
	public static void Main(String[] args)
	{
		Matching task = new Matching();
		// Given text
		String text = "LXYZHEQXYZXYZQQHE11HXYZ1E";
		// Search pattern
		String pattern = "XYZ";
		// Find pattern which occurs in given text
		/*
		    Text = LXYZHEQXYZXYZQQHE11HXYZ1E
		    Pattern = XYZ
		    --------------------------------
		    ➀  LXYZHEQXYZXYZQQHE11HXYZ1E
		        ---
		    ➁  LXYZHEQXYZXYZQQHE11HXYZ1E 
		              ---
		    ➂  LXYZHEQXYZXYZQQHE11HXYZ1E 
		                 ---
		    ➃  LXYZHEQXYZXYZQQHE11HXYZ1E 
		                            ---
		*/
		task.findPattern(text, pattern);
	}
}

Output

Pattern found at index 1
Pattern found at index 7
Pattern found at index 10
Pattern found at index 20
package main
import "fmt"
// Go program for
// Boyer moore algorithm for pattern searching
type Matching struct {}
func getMatching() * Matching {
	var me *Matching = &Matching {}
	return me
}
func(this Matching) max(a,b int) int {
	
	if a > b {
		
		return a
	}
	return b
}
func(this Matching) findPattern(text, pattern string) {
	// Get the length of given text
	var n int = len(text)
	// Get the length of given pattern
	var m int = len(pattern)
	// Possible character
	var badchar = make([] int, 256)
	// Set initial frequency
	for i := 0 ; i < 256 ; i++ {
		badchar[i] = -1
	}
	// Set pattern character position
	for i := 0 ; i < m ; i++ {
		badchar[pattern[i]] = i
	}
	var j int = m - 1
	var s int = 0
	for (s <= (n - m)) {
		for (j >= 0 && pattern[j] == text[s + j]) {
			j--
		}
		if j < 0 {
			fmt.Println("Pattern found at index ", s)
			if s + m < n {
				s += m - badchar[text[s + m]]
			} else {
				s += 1
			}
		} else {
			s += this.max(1, j - badchar[text[s + j]])
		}
		// Rest the value of j
		j = m - 1
	}
}
func main() {
	var task * Matching = getMatching()
	// Given text
	var text string = "LXYZHEQXYZXYZQQHE11HXYZ1E"
	// Search pattern
	var pattern string = "XYZ"
	// Find pattern which occurs in given text
	/*
	    Text = LXYZHEQXYZXYZQQHE11HXYZ1E
	    Pattern = XYZ
	    --------------------------------
	    ➀  LXYZHEQXYZXYZQQHE11HXYZ1E
	        ---
	    ➁  LXYZHEQXYZXYZQQHE11HXYZ1E 
	              ---
	    ➂  LXYZHEQXYZXYZQQHE11HXYZ1E 
	                 ---
	    ➃  LXYZHEQXYZXYZQQHE11HXYZ1E 
	                            ---
	*/
	task.findPattern(text, pattern)
}

Output

Pattern found at index 2
Pattern found at index 5
Pattern found at index 6
<?php
// Php program for
// Boyer moore algorithm for pattern searching
class Matching
{
	public	function findPattern($text, $pattern)
	{
		// Get the length of given text
		$n = strlen($text);
		// Get the length of given pattern
		$m = strlen($pattern);
		// 256 Possible character
		// Set initial frequency -1
		$badchar = array_fill(0, 256, -1);
		// Set pattern character position
		for ($i = 0; $i < $m; ++$i)
		{
			$badchar[ord($pattern[$i])] = $i;
		}
		$j = $m - 1;
		$s = 0;
		while ($s <= ($n - $m))
		{
			while ($j >= 0 && $pattern[$j] == $text[$s + $j])
			{
				$j--;
			}
			if ($j < 0)
			{
				echo("Pattern found at index ".$s."\n");
				if ($s + $m < $n)
				{
					$s += $m - $badchar[ord($text[$s + $m])];
				}
				else
				{
					$s += 1;
				}
			}
			else
			{
				$s += max(1, $j - $badchar[ord($text[$s + $j])]);
			}
			// Rest the value of j
			$j = $m - 1;
		}
	}
}

function main()
{
	$task = new Matching();
	// Given text
	$text = "LXYZHEQXYZXYZQQHE11HXYZ1E";
	// Search pattern
	$pattern = "XYZ";
	// Find pattern which occurs in given text
	/*
	    Text = LXYZHEQXYZXYZQQHE11HXYZ1E
	    Pattern = XYZ
	    --------------------------------
	    ➀  LXYZHEQXYZXYZQQHE11HXYZ1E
	        ---
	    ➁  LXYZHEQXYZXYZQQHE11HXYZ1E 
	              ---
	    ➂  LXYZHEQXYZXYZQQHE11HXYZ1E 
	                 ---
	    ➃  LXYZHEQXYZXYZQQHE11HXYZ1E 
	                            ---
	*/
	$task->findPattern($text, $pattern);
}
main();

Output

Pattern found at index 1
Pattern found at index 7
Pattern found at index 10
Pattern found at index 20
// Node JS program for
// Boyer moore algorithm for pattern searching
class Matching
{
	findPattern(text, pattern)
	{
		// Get the length of given text
		var n = text.length;
		// Get the length of given pattern
		var m = pattern.length;
		// 256 Possible character
		// Set initial frequency -1
		var badchar = Array(256).fill(-1);
		// Set pattern character position
		for (var i = 0; i < m; ++i)
		{
			badchar[pattern.charAt(i).charCodeAt(0)] = i;
		}
		var j = m - 1;
		var s = 0;
		while (s <= (n - m))
		{
			while (j >= 0 && pattern.charAt(j) == text.charAt(s + j))
			{
				j--;
			}
			if (j < 0)
			{
				console.log("Pattern found at index " + s);
				if (s + m < n)
				{
					s += m - badchar[text.charCodeAt(s + m)];
				}
				else
				{
					s += 1;
				}
			}
			else
			{
				s += Math.max(1, j - 
                              badchar[text.charCodeAt(s + j)]);
			}
			// Rest the value of j
			j = m - 1;
		}
	}
}

function main()
{
	var task = new Matching();
	// Given text
	var text = "LXYZHEQXYZXYZQQHE11HXYZ1E";
	// Search pattern
	var pattern = "XYZ";
	// Find pattern which occurs in given text
	/*
	    Text = LXYZHEQXYZXYZQQHE11HXYZ1E
	    Pattern = XYZ
	    --------------------------------
	    ➀  LXYZHEQXYZXYZQQHE11HXYZ1E
	        ---
	    ➁  LXYZHEQXYZXYZQQHE11HXYZ1E 
	              ---
	    ➂  LXYZHEQXYZXYZQQHE11HXYZ1E 
	                 ---
	    ➃  LXYZHEQXYZXYZQQHE11HXYZ1E 
	                            ---
	*/
	task.findPattern(text, pattern);
}
main();

Output

Pattern found at index 1
Pattern found at index 7
Pattern found at index 10
Pattern found at index 20
#  Python 3 program for
#  Boyer moore algorithm for pattern searching
class Matching :
	def max(self, a, b) :
		if (a > b) :
			return a
		
		return b
	
	def findPattern(self, text, pattern) :
		#  Get the length of given text
		n = len(text)
		#  Get the length of given pattern
		m = len(pattern)
		#  256 Possible character
		#  Set initial frequency -1
		badchar = [-1] * (256)
		i = 0
		#  Set pattern character position
		while (i < m) :
			badchar[ord(pattern[i])] = i
			i += 1
		
		j = m - 1
		s = 0
		while (s <= (n - m)) :
			while (j >= 0 and pattern[j] == text[s + j]) :
				j -= 1
			
			if (j < 0) :
				print("Pattern found at index ", s)
				if (s + m < n) :
					s += m - badchar[ord(text[s + m])]
				else :
					s += 1
				
			else :
				s += self.max(1, j - badchar[ord(text[s + j])])
			
			#  Rest the value of j
			j = m - 1
		
	

def main() :
	task = Matching()
	#  Given text
	text = "LXYZHEQXYZXYZQQHE11HXYZ1E"
	#  Search pattern
	pattern = "XYZ"
	#  Find pattern which occurs in given text
	#    Text = LXYZHEQXYZXYZQQHE11HXYZ1E
	#    Pattern = XYZ
	#    --------------------------------
	#    ➀  LXYZHEQXYZXYZQQHE11HXYZ1E
	#        ---
	#    ➁  LXYZHEQXYZXYZQQHE11HXYZ1E 
	#              ---
	#    ➂  LXYZHEQXYZXYZQQHE11HXYZ1E 
	#                 ---
	#    ➃  LXYZHEQXYZXYZQQHE11HXYZ1E 
	#                           ---
	task.findPattern(text, pattern)

if __name__ == "__main__": main()

Output

Pattern found at index  1
Pattern found at index  7
Pattern found at index  10
Pattern found at index  20
#  Ruby program for
#  Boyer moore algorithm for pattern searching
class Matching 
	def max(a, b) 
		if (a > b) 
			return a
		end

		return b
	end

	def findPattern(text, pattern) 
		#  Get the length of given text
		n = text.length
		#  Get the length of given pattern
		m = pattern.length
		#  256 Possible character
		#  Set initial frequency -1
		badchar = Array.new(256) {-1}
		i = 0
		#  Set pattern character position
		while (i < m) 
			badchar[pattern[i].ord] = i
			i += 1
		end

		j = m - 1
		s = 0
		while (s <= (n - m)) 
			while (j >= 0 && pattern[j] == text[s + j]) 
				j -= 1
			end

			if (j < 0) 
				print("Pattern found at index ", s, "\n")
				if (s + m < n) 
					s += m - badchar[text[s + m].ord]
				else
 
					s += 1
				end

			else
 
				s += self.max(1, j - badchar[text[s + j].ord])
			end

			#  Rest the value of j
			j = m - 1
		end

	end

end

def main() 
	task = Matching.new()
	#  Given text
	text = "LXYZHEQXYZXYZQQHE11HXYZ1E"
	#  Search pattern
	pattern = "XYZ"
	#  Find pattern which occurs in given text
	#    Text = LXYZHEQXYZXYZQQHE11HXYZ1E
	#    Pattern = XYZ
	#    --------------------------------
	#    ➀  LXYZHEQXYZXYZQQHE11HXYZ1E
	#        ---
	#    ➁  LXYZHEQXYZXYZQQHE11HXYZ1E 
	#              ---
	#    ➂  LXYZHEQXYZXYZQQHE11HXYZ1E 
	#                 ---
	#    ➃  LXYZHEQXYZXYZQQHE11HXYZ1E 
	#                            ---
	task.findPattern(text, pattern)
end

main()

Output

Pattern found at index 1
Pattern found at index 7
Pattern found at index 10
Pattern found at index 20

import scala.collection.mutable._;
// Scala program for
// Boyer moore algorithm for pattern searching
class Matching()
{
	def max(a: Int, b: Int): Int = {
		if (a > b)
		{
			return a;
		}
		return b;
	}
	def findPattern(text: String, pattern: String): Unit = {
		// Get the length of given text
		var n: Int = text.length();
		// Get the length of given pattern
		var m: Int = pattern.length();
		// 256 Possible character
		// Set initial frequency -1
		var badchar: Array[Int] = Array.fill[Int](256)(-1);
		var i: Int = 0;
		// Set pattern character position
		while (i < m)
		{
			badchar(pattern.charAt(i)) = i;
			i += 1;
		}
		var j: Int = m - 1;
		var s: Int = 0;
		while (s <= (n - m))
		{
			while (j >= 0 && 
                   pattern.charAt(j) == text.charAt(s + j))
			{
				j -= 1;
			}
			if (j < 0)
			{
				println("Pattern found at index " + s);
				if (s + m < n)
				{
					s += m - badchar(text.charAt(s + m));
				}
				else
				{
					s += 1;
				}
			}
			else
			{
				s += max(1, j - badchar(text.charAt(s + j)));
			}
			// Rest the value of j
			j = m - 1;
		}
	}
}
object Main
{
	def main(args: Array[String]): Unit = {
		var task: Matching = new Matching();
		// Given text
		var text: String = "LXYZHEQXYZXYZQQHE11HXYZ1E";
		// Search pattern
		var pattern: String = "XYZ";
		// Find pattern which occurs in given text
		/*
		    Text = LXYZHEQXYZXYZQQHE11HXYZ1E
		    Pattern = XYZ
		    --------------------------------
		    ➀  LXYZHEQXYZXYZQQHE11HXYZ1E
		        ---
		    ➁  LXYZHEQXYZXYZQQHE11HXYZ1E 
		              ---
		    ➂  LXYZHEQXYZXYZQQHE11HXYZ1E 
		                 ---
		    ➃  LXYZHEQXYZXYZQQHE11HXYZ1E 
		                            ---
		*/
		task.findPattern(text, pattern);
	}
}

Output

Pattern found at index 1
Pattern found at index 7
Pattern found at index 10
Pattern found at index 20
import Foundation;
// Swift 4 program for
// Boyer moore algorithm for pattern searching
class Matching
{
	func max(_ a: Int, _ b: Int) -> Int
	{
		if (a > b)
		{
			return a;
		}
		return b;
	}
	func findPattern(_ t: String, _ p: String)
	{
      	let text = Array(t);
      	let pattern = Array(p);
		// Get the length of given text
		let n: Int = text.count;
		// Get the length of given pattern
		let m: Int = pattern.count;
		// 256 Possible character
		// Set initial frequency -1
		var badchar: [Int] = Array(repeating: -1, count: 256);
		var i: Int = 0;
		// Set pattern character position
		while (i < m)
		{
			badchar[Int(UnicodeScalar(
              String(pattern[i]))!.value)] = i;
			i += 1;
		}
		var j: Int = m - 1;
		var s: Int = 0;
		while (s <= (n - m))
		{
			while (j >= 0 && pattern[j] == text[s + j])
			{
				j -= 1;
			}
			if (j < 0)
			{
				print("Pattern found at index ", s);
				if (s + m < n)
				{
					s += m - badchar[
                      Int(UnicodeScalar(String(text[s + m]))!.value)];
				}
				else
				{
					s += 1;
				}
			}
			else
			{
				s += self.max(1, j - 
                              badchar[Int(UnicodeScalar(
                                String(text[s + j]))!.value)]);
			}
			// Rest the value of j
			j = m - 1;
		}
	}
}
func main()
{
	let task: Matching = Matching();
	// Given text
	let text: String = "LXYZHEQXYZXYZQQHE11HXYZ1E";
	// Search pattern
	let pattern: String = "XYZ";
	// Find pattern which occurs in given text
	/*
	    Text = LXYZHEQXYZXYZQQHE11HXYZ1E
	    Pattern = XYZ
	    --------------------------------
	    ➀  LXYZHEQXYZXYZQQHE11HXYZ1E
	        ---
	    ➁  LXYZHEQXYZXYZQQHE11HXYZ1E 
	              ---
	    ➂  LXYZHEQXYZXYZQQHE11HXYZ1E 
	                 ---
	    ➃  LXYZHEQXYZXYZQQHE11HXYZ1E 
	                            ---
	*/
	task.findPattern(text, pattern);
}
main();

Output

Pattern found at index  1
Pattern found at index  7
Pattern found at index  10
Pattern found at index  20
// Kotlin program for
// Boyer moore algorithm for pattern searching
class Matching
{
	fun max(a: Int, b: Int): Int
	{
		if (a > b)
		{
			return a;
		}
		return b;
	}
	fun findPattern(text: String, pattern: String): Unit
	{
		// Get the length of given text
		val n: Int = text.length;
		// Get the length of given pattern
		val m: Int = pattern.length;
		// 256 Possible character
		// Set initial frequency -1
		val badchar: Array < Int > = Array(256)
		{
			0
		};
		var i: Int = 0;
		// Set pattern character position
		while (i < m)
		{
			badchar[pattern.get(i).toInt()] = i;
			i += 1;
		}
		var j: Int = m - 1;
		var s: Int = 0;
		while (s <= (n - m))
		{
			while (j >= 0 && pattern.get(j) == text.get(s + j))
			{
				j -= 1;
			}
			if (j < 0)
			{
				println("Pattern found at index " + s);
				if (s + m < n)
				{
					s += m - badchar[text.get(s + m).toInt()];
				}
				else
				{
					s += 1;
				}
			}
			else
			{
				s += this.max(1, j - badchar[text.get(s + j).toInt()]);
			}
			// Rest the value of j
			j = m - 1;
		}
	}
}
fun main(args: Array < String > ): Unit
{
	val task: Matching = Matching();
	// Given text
	val text: String = "LXYZHEQXYZXYZQQHE11HXYZ1E";
	// Search pattern
	val pattern: String = "XYZ";
	// Find pattern which occurs in given text
	/*
	    Text = LXYZHEQXYZXYZQQHE11HXYZ1E
	    Pattern = XYZ
	    --------------------------------
	    ➀  LXYZHEQXYZXYZQQHE11HXYZ1E
	        ---
	    ➁  LXYZHEQXYZXYZQQHE11HXYZ1E 
	              ---
	    ➂  LXYZHEQXYZXYZQQHE11HXYZ1E 
	                 ---
	    ➃  LXYZHEQXYZXYZQQHE11HXYZ1E 
	                           ---
	*/
	task.findPattern(text, pattern);
}

Output

Pattern found at index 1
Pattern found at index 7
Pattern found at index 10
Pattern found at index 20
Last updated on by Kalkicode




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