Merge branch 'master' of https://github.com/OpenGenus/cosmos into aut…

…oformat-js

README.md

@@ -43,7 +43,7 @@ Each type has several hundreds of problems with solutions in several languages s
 
 # Maintainers
 
-This is a massive collaboration and to keep the quality intact and drive the vision in the proper direction, we have maintainers.
+This is a massive collaboration. Hence, to keep the quality intact and drive the vision in the proper direction, we have maintainers.
 
 > Maintainers are your friends forever. They are vastly different from moderators.
 

code/data_structures/src/linked_list/linked_list.js

@@ -0,0 +1,71 @@
+class LinkedList {
+    constructor(value) {
+        this.head = null;
+        this.length = 0;
+        this.addToHead(value);
+    }
+
+    addToHead(value) {
+        const newNode = { value };
+        newNode.next = this.head;
+        this.head = newNode;
+        this.length++;
+        return this;
+    }
+
+    removeFromHead() {
+        if (this.length === 0) {
+            return undefined;
+        }
+
+        const value = this.head.value;
+        this.head = this.head.next;
+        this.length--;
+
+        return value;
+    }
+
+    find(val) {
+        let thisNode = this.head;
+
+        while(thisNode) {
+            if(thisNode.value === val) {
+                return thisNode;
+            }
+
+            thisNode = thisNode.next;
+        }
+
+        return thisNode;
+    }
+
+    remove(val) {
+        if(this.length === 0) {
+            return undefined;
+        }
+
+        if (this.head.value === val) {
+            return this.removeFromHead();
+        }
+
+        let previousNode = this.head;
+        let thisNode = previousNode.next;
+
+        while(thisNode) {
+            if(thisNode.value === val) {
+                break;
+            }
+
+            previousNode = thisNode;
+            thisNode = thisNode.next;
+        }
+
+        if (thisNode === null) {
+            return undefined;
+        }
+
+        previousNode.next = thisNode.next;
+        this.length--;
+        return this;
+    }
+}

code/data_structures/src/list/circular_linked_list/circular_linked_list.java → code/data_structures/src/list/circular_linked_list/CircularLinkedList.java

@@ -1,155 +1,109 @@
 import java.util.Scanner;
 
 // Part of Cosmos by OpenGenus Foundation
+public class CircularLinkedList {
 
-public class circular_linked_list {
+    Node head, tail;
 
     // Node Class
-
     class Node {
-
         int value;
         Node next;
 
         public Node(int value, Node next) {
-
             this.value = value;
             this.next = next;
-
         }
-
     }
 
     // Manipulation Methods
-
     public void Add(int value) {
-
         Node n = new Node(value, head);
         if (head == null) {
-
             head = n;
             tail = n;
             n.next = n;
-
         }
         else {
-
             tail.next = n;
             tail = n;
-
         }
-
     }
 
     public void Remove(int value) {
-
         Node aux = head;
         Node prev = tail;
         boolean found = false;
 
         // Find the node with the value
-
         if (aux == null) return;
         if (aux == head && aux.value == value) { found = true; }
         else {
-
             prev = aux;
             aux = aux.next;
             while (aux != head) {
-
                 if (aux.value == value) {
                     found = true;
                     break;
                 }
-
                 prev = aux;
                 aux = aux.next;
             }
-
         }
 
         // If found, remove it
-
         if (!found) return;
         if (aux == head && aux == tail) { head = tail = null; }
         else {
             if (aux == head) head = aux.next;
             if (aux == tail) tail = prev;
             prev.next = aux.next;
         }
-
     }
 
     public void Print() {
-
         if (head == null) return;
-
         System.out.print(head.value + " ");
-
         Node aux = head.next;
         while (aux != head) { System.out.print(aux.value + " "); aux = aux.next; }
         System.out.println();
         System.out.println("HEAD is " + head.value);
         System.out.println("TAIL is " + tail.value);
-
     }
 
-    // 
-
-    Node head, tail;
-
     // Example Usage
-
     public static void main(String[] args) {
-
         int selection = 0;
         Scanner input = new Scanner(System.in);
-        circular_linked_list list = new circular_linked_list();
+        CircularLinkedList list = new CircularLinkedList();
 
         do {
-
             System.out.print("1. Insert\n2. Remove\n3. Print\n> ");
             selection = input.nextInt();
 
             if (selection == 1) {
-
                 System.out.print("Enter Value to Insert: ");
                 int value = input.nextInt();
-
                 list.Add(value);
                 list.Print();
-
                 System.out.print("\n");
-
             }
             else if (selection == 2) {
-
                 System.out.print("Enter Value to Remove: ");
                 int value = input.nextInt();
-
                 list.Remove(value);
                 list.Print();
-
                 System.out.println("\n");
-
             }
             else if (selection == 3) {
-
                 list.Print();
                 System.out.println("\n");
-
             }
             else {
-
                 System.out.println("Invalid Selection. Exiting");
-
             }
-
         }
         while (selection > 0 && selection < 4);
-
         input.close();
-
     }
-
-}
+}

code/data_structures/src/list/doubly_linked_list/doubly_linked_list.java → code/data_structures/src/list/doubly_linked_list/DoublyLinkedList.java

@@ -25,9 +25,7 @@ class DoublyLinkedList {
 	private Node last;
 	private int n = 0;  //size
 
-
 	/*-----Insert Method-----*/
-
 	public void insert(int pos, int data){
 		if (pos > n + 1){
 			pos = n + 1;
@@ -75,7 +73,6 @@ public void insert(int pos, int data){
 	}
 
 	/*-----Delete Method-----*/
-
 	public void delete(int pos){
 		if (n == 0) {
 			System.out.println("List is Empty!");
@@ -86,6 +83,12 @@ public void delete(int pos){
 			pos = n;
 		}
 
+		if (pos == 1) {
+			first = first.next;
+			first.prev = null;
+			return;
+		}
+
 		int c = 1;
 		Node cur = first;
 
@@ -94,16 +97,16 @@ public void delete(int pos){
 			cur = cur.next;
 		}
 
-
-		cur.prev.next = cur.next;
-		cur.next.prev = cur.prev;
-
+		if (cur.prev != null) {
+			cur.prev.next = cur.next;
+		}
+		if (cur.next != null) {
+			cur.next.prev = cur.prev;
+		}
 		n--;
-
 	}
 
 	/*-----Print in forward direction-----*/
-
 	public void display() {
 		Node cur = first;
 
@@ -116,7 +119,6 @@ public void display() {
 	}
 
 	/*-----Print in reverse direction-----*/
-
 	public void reverseDisplay() {
 		Node cur = last;
 
@@ -145,11 +147,14 @@ public static void main(String[] args) {
 
 			switch(c) {
 				case 1:
+					System.out.println("Enter insertion position");
 					int pos = sc.nextInt();
+					System.out.println("Enter value");
 					int val = sc.nextInt();
 					l.insert(pos, val);
 					break;
 				case 2:
+					System.out.println("Enter deletion position");
 					pos = sc.nextInt();
 					l.delete(pos);
 					break;

code/data_structures/src/queue/README.md

@@ -15,3 +15,8 @@ Functions
 - size()
 --Returns the size of the queue
 
+## Time Complexity
+- Enqueue - O(1)
+- Dequeue - O(1)
+- size    - O(1)
+- front - O(n)

code/data_structures/src/stack/balanced_expression/balanced_expression.c

@@ -0,0 +1,66 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct stack {
+	char data;
+	struct stack* next;
+} stack;
+
+void
+push(stack** top, char data) {
+    stack* new = (stack*) malloc(sizeof(stack));
+    new->data = data;
+    new->next = *top;
+    *top = new;
+}
+
+char
+peek(stack* top) {
+    return ( top -> data );
+}
+
+int
+empty(stack* top) {
+    return (top == NULL);
+}
+
+void
+pop(stack** top) {
+    stack* temp = *top;
+    *top = (*top)->next;
+    free(temp);
+    temp = NULL;    
+}
+
+int
+checkBalanced(char *s) {
+	int len = strlen(s);
+	if (len % 2 != 0) return 0;
+	stack *head = NULL;
+	for (int i = 0;i < len ;i++) {
+		if (s[i] == '{' || s[i] == '[' || s[i] == '(') {
+			push(&head, s[i]);
+		}
+		else {
+			char temp = peek(head);
+			if (s[i] == '}' && temp == '{') pop(&head);
+			else if (s[i] == ']' && temp == '[') pop(&head);
+			else if (s[i] == ')' && temp == '(') pop(&head);
+			else return 0;
+		}
+	}
+	return (empty(head));
+}
+
+int
+main()
+{
+	char *s = (char*) malloc(sizeof(char) * 100);
+	printf("Enter the expression\n");
+	scanf("%[^\n]s" , s);
+	int res = checkBalanced(s);
+	if (res) printf("Expression is valid\n");
+	else printf("Expression is not valid\n");
+	return 0;
+}