Skip to main content

Find the longest common prefix using Trie

Here given code implementation process.

//C++ program
//Find the Longest Common Prefix using Trie

#include<iostream>

#include<string>

#define ALPHABETS 26
using namespace std;
class Node {
  public:
    bool end;
  Node *children[ALPHABETS];
  Node() {
    this->end = false;
    for (int i = 0; i < ALPHABETS; ++i) {
      this->children[i] = NULL;
    }
  }
};
class Trie {
  public:
    Node *root;
  Trie() {
    this->root = new Node();
  }
  void insert(string text) {
    int length = text.size();
    int index = 0;
    Node *head = this->root;
    for (int level = 0; level < length; level++) {
      index = text[level] - 'a';
      if (head->children[index] == NULL) {
        head->children[index] = new Node();
      }
      head = head->children[index];
    }
    if (head != NULL) {
      head->end = true;
    }
  }
  void longestPrefix(Node *head, int same) {
    if (head != NULL) {
      int location = -1;
      bool status = true;
      for (int i = 0; i < ALPHABETS && status; i++) {
        if (head->children[i] != NULL) {
          if (location == -1) {
            location = i;
          }
          if (i != location) {
            status = false;
          }

        }
      }
      if (status == true) {
        cout << ((char)(location + 97));
        this->longestPrefix(head->children[location], same + 1);
      } else if (status == false && same == 0) {
        cout << "No Longest Prefix" << endl;
      }

    }
  }
};
int main() {
  Trie obj;
  //Insert following data
  obj.insert("cool");
  obj.insert("coder");
  obj.insert("confirm");
  obj.insert("cow");

  obj.longestPrefix(obj.root, 0);
  cout << endl;
}

Output

co
/*
  Java program
  Find the Longest Common Prefix using Trie
*/

class Node {
  //Indicates end of string
  public boolean end;

  public Node[] children;

  public Node(int size) {
    end = false;
    children = new Node[size];
  }
}
public class Trie 
{ 
  public int ALPHABETS = 26;
  public Node root; 

  public Trie()
  {
    root = new Node(ALPHABETS);
  }

  public void insert(String text)
  {
    //first get the length of text
    int length = text.length();
    
    //This variable are used to task find the index location of character
    int index = 0;
    
    //get the root node
    Node head = root;

    for (int level = 0; level < length ; level++ )
    {
      //Get the index
      index = text.charAt(level)-'a';

      if(head.children[index] == null)
      {
        //When need to add new Node
        head.children[index] = new Node(ALPHABETS);
      }

      head = head.children[index];
    }
    if(head != null)
    {  
      //indicates end of string
      head.end = true;
    }
  }
  public void longestPrefix(Node head,int same)
  {
    if (head != null) {
      int location = -1;
      boolean status = true;
      for (int i = 0; i < ALPHABETS && status; i++) {
        if (head.children[i] != null) {
          if (location == -1) {
            location = i;
          }
          if (i != location) {
            status = false;
          }

        }
      }
      if (status == true) {
        System.out.print((char)(location+97));
        longestPrefix(head.children[location], same + 1);
      } else if (status == false && same == 0) {
       
        System.out.print("No Longest Prefix");
      }

    }
    
  }
 
  public static void main(String[] args) 
  {
    //Make object
    Trie obj = new Trie();

   
    obj.insert("cool");
    obj.insert("coder");
    obj.insert("confirm");
    obj.insert("cow");
    
    obj.longestPrefix(obj.root,0);
    System.out.println();
  }
}

Output

co
/*
  C# program
  Find the Longest Common Prefix using Trie
*/
using System;
public class Node {
	//Indicates end of string
	public Boolean end;

	public Node[] children;

	public Node(int size) {
		end = false;
		children = new Node[size];
	}
}
public class Trie 
{ 
	public int ALPHABETS = 26;
	public Node root; 

	public Trie()
	{
		root = new Node(ALPHABETS);
	}

	public void insert(String text) {
		//first get the.Length of text
		int size = text.Length;

		//This variable are used to task find the index location of character
		int index = 0;

		//get the root node
		Node head = root;

		for (int level = 0; level < size; level++) {
			//Get the index
			index = text[level] - 'a';

			if (head.children[index] == null) {
				//When need to add new Node
				head.children[index] = new Node(ALPHABETS);
			}

			head = head.children[index];
		}
		if (head != null) {
			//indicates end of string
			head.end = true;
		}
	}
	public void longestPrefix(Node head,int same)
	{
		if (head != null) {
			int location = -1;
			Boolean status = true;
			for (int i = 0; i < ALPHABETS && status; i++) {
				if (head.children[i] != null) {
					if (location == -1) {
						location = i;
					}
					if (i != location) {
						status = false;
					}

				}
			}
			if (status == true) {
				Console.Write((char)(location+97));
				longestPrefix(head.children[location], same + 1);
			} else if (status == false && same == 0) {

				Console.Write("No Longest Prefix");
			}

		}

	}

	public static void Main(String[] args) 
	{
		//Make object
		Trie obj = new Trie();


		obj.insert("cool");
		obj.insert("coder");
		obj.insert("confirm");
		obj.insert("cow");

		obj.longestPrefix(obj.root,0);
		Console.WriteLine();
	}
}

Output

co
# Ruby Program
# Find the Longest Common Prefix using Trie
class Node 
	attr_reader :end, :children
    attr_accessor :end, :children
	def initialize(size) 
		@end = false
		@children = Array.new(size){nil}
	end
end

class Trie 
	attr_reader :ALPHABETS, :root
    attr_accessor :ALPHABETS, :root
	def initialize() 
        @ALPHABETS = 26
		@root = Node.new(@ALPHABETS)
	end
	def insert(text) 
		length = text.length()
		location = 0
		head = @root
		level = 0
		while (level < length) 
			location = text[level].ord - 'a'.ord
			if (head.children[location] == nil) 
				head.children[location] = Node.new(@ALPHABETS)
			end
			head = head.children[location]
			level += 1
		end
		if (head != nil) 
			head.end = true
		end
	end
	def longestPrefix(head, same) 
		if (head != nil) 
			location = -1
			status = true
			i = 0
			while (i < @ALPHABETS and status==true) 
				if (head.children[i] != nil) 
					if (location == -1) 
						location = i
					elsif (i != location) 
						status = false
					end
				end
				i += 1
			end
			if (status == true) 
				print((location + 97).chr)
				self.longestPrefix(head.children[location], same + 1)
			elsif (status == false and same == 0) 
				print("No Longest Prefix")
			end
		end
	end
end
def main() 
	obj = Trie.new()
	obj.insert("cool")
	obj.insert("coder")
	obj.insert("confirm")
	obj.insert("cow")
	obj.longestPrefix(obj.root,0)
	print("\n")
end
main()

Output

co
# Python Program
# Find the Longest Common Prefix using Trie
class Node :

  def __init__(self, size) :
    self.end = False;
    self.children = [None]*size;
  

class Trie :
  

  def __init__(self) :
    self.ALPHABETS = 26;
    self.root = Node(self.ALPHABETS);
  
  def insert(self, text) :
    length = len(text)
    index = 0
    head = self.root
    level = 0
    while (level < length) :
      index = ord(text[level]) - ord('a')
      if (head.children[index] == None) :
        head.children[index] = Node(self.ALPHABETS)
      
      head = head.children[index]
      level += 1
    
    if (head != None) :
      head.end = True
     
  
  def longestPrefix(self, head, same) :
    if (head != None) :
      location = -1;
      status = True;
      i = 0;
      while (i < self.ALPHABETS and status) :
        if (head.children[i] != None) :
          if (location == -1) :
            location = i;
          
          if (i != location) :
            status = False;
          
        
        i += 1;
      
      if (status == True) :
        print(chr(location + 97),end="")
        self.longestPrefix(head.children[location], same + 1);
      elif (status == False and same == 0) :
        print("No Longest Prefix");
    
  
def main() :
  obj = Trie();
  obj.insert("cool");
  obj.insert("coder");
  obj.insert("confirm");
  obj.insert("cow");
  obj.longestPrefix(obj.root,0);
  print();
  

if __name__ == "__main__":
  main()

Output

co
/*
  Node JS Program
  Find the Longest Common Prefix using Trie
*/
class Node {

	constructor(size) {
		this.end = false;
		this.children =  new Array(size).fill(null);
	}
}
class Trie {
	
	constructor() {
		this.ALPHABETS = 26;
		this.root = new Node(this.ALPHABETS);
	}
	insert(text) {
		var length = text.length;
		var index = 0;
		var head = this.root;
		var level = 0;
		while (level < length) {
			index = text.charCodeAt(level) - 'a'.charCodeAt(0);;
			if (head.children[index] == null) {
				head.children[index] = new Node(this.ALPHABETS);
			}
			head = head.children[index];
			level++;
		}
		if (head != null) {
			head.end = true;
		}
	}
	longestPrefix(head, same) {
		if (head != null) {
			var location = -1;
			var status = true;
			var i = 0;
			while (i < this.ALPHABETS && status) {
				if (head.children[i] != null) {
					if (location == -1) {
						location = i;
					}
					if (i != location) {
						status = false;
					}
				}
				i++;
			}
			if (status == true) {
				process.stdout.write(String.fromCharCode(location + 97));
				this.longestPrefix(head.children[location], same + 1);
			} else
			if (status == false && same == 0) {
				process.stdout.write("No Longest Prefix");
			}
		}
	}
}

function main() {
	var obj = new Trie();
	obj.insert("cool");
	obj.insert("coder");
	obj.insert("confirm");
	obj.insert("cow");
	obj.longestPrefix(obj.root,0);
	process.stdout.write("\n");
}
main();

Output

co
<?php
/*
  Php Program
  Find the Longest Common Prefix using Trie
*/
class Node {
  public $end;
  public $children;

  function __construct($size) {
    $this->end = false;
    $this->children = array_fill(0, $size, null);
  }
}
class Trie {
  public $ALPHABETS = 26;
  public $root;

  function __construct() {
    $this->root = new Node($this->ALPHABETS);
  }
  public  function insert($text) {
    $length = strlen($text);
    $index = 0;
    $head = $this->root;
    $level = 0;
    while ($level < $length) {
      $index = ord($text[$level]) - ord('a');
      if ($head->children[$index] == null) {
        $head->children[$index] = new Node($this->ALPHABETS);
      }
      $head = $head->children[$index];
      $level++;
    }
    if ($head != null) {
      $head->end = true;
    }
  }
  public function longestPrefix($head, $same) {
    if ($head != null) {
      $location = -1;
      $status = true;
      $i = 0;
      while ($i < $this->ALPHABETS && $status) {
        if ($head->children[$i] != null) {
          if ($location == -1) {
            $location = $i;
          }
          if ($i != $location) {
            $status = false;
          }
        }
        $i++;
      }
      if ($status == true) {
        echo(chr($location + 97));
        $this->longestPrefix($head->children[$location], $same + 1);
      } else
      if ($status == false && $same == 0) {
        echo("No Longest Prefix");
      }
    }
  
  }
}
function main() {
    $obj = new Trie();
    $obj->insert("cool");
    $obj->insert("coder");
    $obj->insert("confirm");
    $obj->insert("cow");
    $obj->longestPrefix($obj->root,0);
    echo ("\n");
}
main();

Output

co
Last updated on by Kalkicode




Comment

Please share your knowledge to improve code and content standard. Also submit your doubts, and test case. We improve by your feedback. We will try to resolve your query as soon as possible.

New Comment