Program to Find the Maximum and Minimum Value Node From a Doubly Linked List

Q. Program to find the maximum and minimum value node from a doubly linked list.

Explanation

In this program, we will create a doubly linked list then, iterate through the list to find out the minimum and maximum node.

Program to find the maximum and minimum value node from a doubly linked list

We will maintain two variables min and max. Min will hold the minimum value node, and max will hold the maximum value node. In above example, 1 will be the minimum value node and 9 will be the maximum value node.

Algorithm

Define a Node class which represents a node in the list. It will have three properties: data, previous which will point to the previous node and next which will point to the next node.
Define another class for creating the doubly linked list, and it has two nodes: head and tail. Initially, head and tail will point to null.
minimumNode() will prints out minimum value node:
1. Define variable min and initialize with head's data.
2. Current will point to head.
3. Iterate through the list by comparing each node's data with min.
4. If min > current's data then min will hold current's data.
5. At the end of the list, variable min will hold the minimum value node.
6. Print the min value.
maximumNode() will prints out maximum value node:
1. Define variable max and initialize with head's data.
2. Current will point to head.
3. Iterate through the list by comparing each node's data with max.
4. If max < current's data then max will hold current?s data.
5. At the end of the list, variable max will hold the maximum value node.
6. Print the max value.

Solution

Python

#Represent a node of doubly linked list
class Node:
    def __init__(self,data):
        self.data = data;
        self.previous = None;
        self.next = None;
        
class MinMax:
    #Represent the head and tail of the doubly linked list
    def __init__(self):
        self.head = None;
        self.tail = None;
        
    #addNode() will add a node to the list
    def addNode(self, data):
        #Create a new node
        newNode = Node(data);
        
        #If list is empty
        if(self.head == None):
            #Both head and tail will point to newNode
            self.head = self.tail = newNode;
            #head's previous will point to None
            self.head.previous = None;
            #tail's next will point to None, as it is the last node of the list
            self.tail.next = None;
        else:
            #newNode will be added after tail such that tail's next will point to newNode
            self.tail.next = newNode;
            #newNode's previous will point to tail
            newNode.previous = self.tail;
            #newNode will become new tail
            self.tail = newNode;
            #As it is last node, tail's next will point to None
            self.tail.next = None;
            
    #MinimumNode() will find out minimum value node in the list
    def minimumNode(self):
        #Node current will point to head
        current = self.head;
        
        #Checks if list is empty
        if(self.head == None):
            print("List is empty");
            return 0;
        else:
            #Initially, min will store the value of head's data
            min = self.head.data;
            while(current != None):
                #If value of min is greater than current's data
                #Then, replace value of min with current node's data
                if(min > current.data):
                    min = current.data;
                current = current.next;
        return min;
        
    #MaximumNode() will find out maximum value node in the list
    def maximumNode(self):
        #Node current will point to head
        current = self.head;
        
        #Checks if list is empty
        if(self.head == None):
            print("List is empty");
            return 0;
        else:
            #Initially, max will store the value of head's data
            max = self.head.data;
            #If value of max is lesser than current's data
            #Then, replace value of max with current node's data
            while(current != None):
                if(current.data > max):
                    max = current.data;
                current = current.next;
        return max;
            
dList = MinMax();
#Add nodes to the list
dList.addNode(5);
dList.addNode(7);
dList.addNode(9);
dList.addNode(1);
dList.addNode(2);
 
#Prints the minimum value node in the list
print("Minimum value node in the list: "+ str(dList.minimumNode()));
#Prints the maximum value node in the list
print("Maximum value node in the list: "+ str(dList.maximumNode()));

Output:

Minimum value node in the list: 1
Maximum value node in the list: 9

C

#include <stdio.h>
 
//Represent a node of the doubly linked list

struct node{
    int data;
    struct node *previous;
    struct node *next;
};    
 
//Represent the head and tail of the doubly linked list
struct node *head, *tail = NULL;
 
//addNode() will add a node to the list
void addNode(int data) {
    //Create a new node
    struct node *newNode = (struct node*)malloc(sizeof(struct node));
    newNode->data = data;
    
    //If list is empty
    if(head == NULL) {
        //Both head and tail will point to newNode
        head = tail = newNode;
        //head's previous will point to NULL
        head->previous = NULL;
        //tail's next will point to NULL, as it is the last node of the list
        tail->next = NULL;
    }
    else {
        //newNode will be added after tail such that tail's next will point to newNode
        tail->next = newNode;
        //newNode's previous will point to tail
        newNode->previous = tail;
        //newNode will become new tail
        tail = newNode;
        //As it is last node, tail's next will point to NULL
        tail->next = NULL;
    }
}
 
//MinimumNode() will find out minimum value node in the list
int minimumNode() {
    //Node current will point to head
    struct node *current = head;
    int min;
    
    //Checks if list is empty
    if(head == NULL) {
        printf("List is empty\n");
        return 0;
    }
    else {
        //Initially, min will store the value of head's data
        min = head->data;
        while(current != NULL) {
            //If value of min is greater than current's data
            //Then, replace value of min with current node's data
            if(min > current->data)
                min = current->data;
            current = current->next;
        }
    }
    return min;
}
 
//MaximumNode() will find out maximum value node in the list
int maximumNode() {
    //Node current will point to head
    struct node *current = head;
    int max;
    
    //Checks if list is empty
    if(head == NULL) {
        printf("List is empty\n");
        return 0;
    }
    else {
        //Initially, max will store the value of head's data
        max = head->data;
        //If value of max is lesser than current's data
        //Then, replace value of max with current node's data
        while(current != NULL) {
            if(current->data > max) 
                max = current->data;
            current = current->next;
        }
    }
    return max;
}
 
int main()
{
    //Add nodes to the list
    addNode(5);
    addNode(7);
    addNode(9);
    addNode(1);
    addNode(2);
    
    //Prints the minimum value node in the list
    printf("Minimum value node in the list: %d\n", minimumNode());
    //Prints the maximum value node in the list
    printf("Maximum value node in the list: %d", maximumNode());
 
    return 0;
}

Output:

Minimum value node in the list: 1
Maximum value node in the list: 9

JAVA

public class MinMax {
    
    //Represent a node of the doubly linked list

    class Node{
        int data;
        Node previous;
        Node next;
        
        public Node(int data) {
            this.data = data;
        }
    }
    
    //Represent the head and tail of the doubly linked list
    Node head, tail = null;
    
    //addNode() will add a node to the list
    public void addNode(int data) {
        //Create a new node
        Node newNode = new Node(data);
        
        //If list is empty
        if(head == null) {
            //Both head and tail will point to newNode
            head = tail = newNode;
            //head's previous will point to null
            head.previous = null;
            //tail's next will point to null, as it is the last node of the list
            tail.next = null;
        }
        else {
            //newNode will be added after tail such that tail's next will point to newNode
            tail.next = newNode;
            //newNode's previous will point to tail
            newNode.previous = tail;
            //newNode will become new tail
            tail = newNode;
            //As it is last node, tail's next will point to null
            tail.next = null;
        }
    }
    
    //MinimumNode() will find out minimum value node in the list
    public int minimumNode() {
        //Node current will point to head
        Node current = head;
        int min;
        
        //Checks if list is empty
        if(head == null) {
            System.out.println("List is empty");
            return 0;
        }
        else {
            //Initially, min will store the value of head's data
            min = head.data;
            while(current != null) {
                //If the value of min is greater than the current's data

                //Then, replace the value of min with current node's data

                if(min > current.data)
                    min = current.data;
                current = current.next;
            }
        }
        return min;
    }
    
    //MaximumNode() will find out maximum value node in the list
    public int maximumNode() {
        //Node current will point to head
        Node current = head;
        int max;
        
        //Checks if list is empty
        if(head == null) {
            System.out.println("List is empty");
            return 0;
        }
        else {
            //Initially, max will store the value of head's data
            max = head.data;
            //If value of max is lesser than current's data
            //Then, replace value of max with current node's data
            while(current != null) {
                if(current.data > max) 
                    max = current.data;
                current = current.next;
            }
        }
        return max;
    }
    
    public static void main(String[] args) {
        
        MinMax dList = new MinMax();
        //Add nodes to the list
        dList.addNode(5);
        dList.addNode(7);
        dList.addNode(9);
        dList.addNode(1);
        dList.addNode(2);
        
        //Prints the minimum value node in the list
        System.out.println("Minimum value node in the list: "+ dList.minimumNode());
        //Prints the maximum value node in the list
        System.out.println("Maximum value node in the list: "+ dList.maximumNode());
    }
}

Output:

Minimum value node in the list: 1
Maximum value node in the list: 9

C#

using System; 
namespace DoublyLinkedList 
{                     
    public class Program
    {
        //Represent a node of the doubly linked list

        public class Node<T>{
            public T data;
            public Node<T> previous;
            public Node<T> next;
            
            public Node(T value) {
                data = value;
            }
        }
        
        public class MinMax<T> where T : IComparable<T>{
            //Represent the head and tail of the doubly linked list
            protected Node<T> head = null;             
             protected Node<T> tail = null;
            
            //addNode() will add a node to the list
            public void addNode(T data) {
                //Create a new node
                Node<T> newNode = new Node<T>(data);
 
                //If list is empty
                if(head == null) {
                    //Both head and tail will point to newNode
                    head = tail = newNode;
                    //head's previous will point to null
                    head.previous = null;
                    //tail's next will point to null, as it is the last node of the list
                    tail.next = null;
                }
                else {
                    //newNode will be added after tail such that tail's next will point to newNode
                    tail.next = newNode;
                    //newNode's previous will point to tail
                    newNode.previous = tail;
                    //newNode will become new tail
                    tail = newNode;
                    //As it is last node, tail's next will point to null
                    tail.next = null;
                }
            }
            
            //MinimumNode() will find out minimum value node in the list
            public T minimumNode() {
                //Node current will point to head
                Node<T> current = head;
                T min;
 
                //Checks if list is empty
                if(head == null) {
                    Console.WriteLine("List is empty");
                    return default(T);
                }
                else {
                    //Initially, min will store the value of head's data
                    min = head.data;
                    while(current != null) {
                        //If value of min is greater than current's data
                        //Then, replace value of min with current node's data
                        if(min.CompareTo(current.data) > 0)
                            min = current.data;
                        current = current.next;
                    }
                }
                return min;
            }
    
            //MaximumNode() will find out maximum value node in the list
            public T maximumNode() {
                //Node current will point to head
                Node<T> current = head;
                T max;
 
                //Checks if list is empty
                if(head == null) {
                    Console.WriteLine("List is empty");
                    return default(T);
                }
                else {
                    //Initially, max will store the value of head's data
                    max = head.data;
                    //If value of max is lesser than current's data
                    //Then, replace value of max with current node's data
                    while(current != null) {
                        if(current.data.CompareTo(max) > 0) 
                            max = current.data;
                        current = current.next;
                    }
                }
                return max;
            }
        }
        
        public static void Main()
        {
            MinMax<int> dList = new MinMax<int>();
            //Add nodes to the list
            dList.addNode(5);
            dList.addNode(7);
            dList.addNode(9);
            dList.addNode(1);
            dList.addNode(2);
 
            //Prints the minimum value node in the list
            Console.WriteLine("Minimum value node in the list: "+ dList.minimumNode());
            //Prints the maximum value node in the list
            Console.WriteLine("Maximum value node in the list: "+ dList.maximumNode());
        }    
    }
}           

Output:

Minimum value node in the list: 1
Maximum value node in the list: 9

PHP

<!DOCTYPE html>
<html>
<body>
<?php
//Represent a node of doubly linked list
class Node{
    public $data;
    public $previous;
    public $next;
    
    function __construct($data){
        $this->data = $data;
    }
}
class MinMax{
    //Represent the head and tail of the doubly linked list
    public $head;
    public $tail;
    function __construct(){
        $this->head = NULL;
        $this->tail = NULL;
    }
    
    //addNode() will add a node to the list
    function addNode($data){
        //Create a new node
        $newNode = new Node($data);
        
        //If list is empty
        if($this->head == NULL) {
            //Both head and tail will point to newNode
            $this->head = $this->tail = $newNode;
            //head's previous will point to NULL
            $this->head->previous = NULL;
            //tail's next will point to NULL, as it is the last node of the list
            $this->tail->next = NULL;
        }
        else {
            //newNode will be added after tail such that tail's next will point to newNode
            $this->tail->next = $newNode;
            //newNode's previous will point to tail
            $newNode->previous = $this->tail;
            //newNode will become new tail
            $this->tail = $newNode;
            //As it is last node, tail's next will point to NULL
            $this->tail->next = NULL;
        }
    }
    
    //MinimumNode() will find out minimum value node in the list
    function minimumNode() {
        //Node current will point to head
        $current = $this->head;
        
        //Checks if list is empty
        if($this->head == NULL) {
            print("List is empty <br>");
            return 0;
        }
        else {
            //Initially, min will store the value of head's data
            $min = $this->head->data;
            while($current != NULL) {
                //If value of min is greater than current's data
                //Then, replace value of min with current node's data
                if($min > $current->data)
                    $min = $current->data;
                $current = $current->next;
            }
        }
        return $min;
    }
    
    //MaximumNode() will find out maximum value node in the list
    function maximumNode() {
        //Node current will point to head
        $current = $this->head;
        
        //Checks if list is empty
        if($this->head == NULL) {
            print("List is empty <br>");
            return 0;
        }
        else {
            //Initially, max will store the value of head's data
            $max = $this->head->data;
            //If value of max is lesser than current's data
            //Then, replace value of max with current node's data
            while($current != NULL) {
                if($current->data > $max) 
                    $max = $current->data;
                $current = $current->next;
            }
        }
        return $max;
    }
}
    
$dList = new MinMax();
//Add nodes to the list
$dList->addNode(5);
$dList->addNode(7);
$dList->addNode(9);
$dList->addNode(1);
$dList->addNode(2);
 
//Prints the minimum value node in the list
print("Minimum value node in the list: " . $dList->minimumNode());
print("<br>");
//Prints the maximum value node in the list
print("Maximum value node in the list: " . $dList->maximumNode());
?>
</body>
</html>

Output:

Minimum value node in the list: 1
Maximum value node in the list: 9

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Q. Program to find the maximum and minimum value node from a doubly linked list.

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