diff --git a/Exercise_1.java b/Exercise_1.java index 314a3cb45..396d22a2f 100644 --- a/Exercise_1.java +++ b/Exercise_1.java @@ -1,35 +1,59 @@ -class Stack { - //Please read sample.java file before starting. - //Kindly include Time and Space complexity at top of each file - static final int MAX = 1000; +class Stack { + + // Time Complexity : O(1) + // Space Complexity : O(n) + // Did this code successfully run on Leetcode : 12/18 test cases passed, the test with inputs ["MyStack","empty"] failed + // Any problem you faced while coding this : No but I did not understand why the Leetcode test case failed + static final int MAX = 1000; int top; int a[] = new int[MAX]; // Maximum size of Stack boolean isEmpty() - { - //Write your code here + { + // If a is empty, return true + return a.length == 0; } Stack() - { - //Initialize your constructor + { + // Initialize the top of the stack to be -1 + top = -1; } boolean push(int x) { //Check for stack Overflow - //Write your code here + if(top == MAX -1 ){ + System.out.println("Stack overflow"); + return false; + } + else { + top++; + a[top] = x; + return true; + } } int pop() { //If empty return 0 and print " Stack Underflow" - //Write your code here + if(top == -1){ + System.out.println("Stack underflow"); + return 0; + } + else { + return a[top--]; + } } int peek() { - //Write your code here + if(isEmpty()){ + return 0; + } + else{ + return a[top]; + } } } diff --git a/Exercise_3.java b/Exercise_3.java deleted file mode 100644 index fb66d329d..000000000 --- a/Exercise_3.java +++ /dev/null @@ -1,70 +0,0 @@ -import java.io.*; - -// Java program to implement -// a Singly Linked List -public class LinkedList { - - Node head; // head of list - - // Linked list Node. - // This inner class is made static - // so that main() can access it - static class Node { - - int data; - Node next; - - // Constructor - Node(int d) - { - //Write your code here - } - } - - // Method to insert a new node - public static LinkedList insert(LinkedList list, int data) - { - // Create a new node with given data - - // If the Linked List is empty, - // then make the new node as head - - // Else traverse till the last node - // and insert the new_node there - - // Insert the new_node at last node - // Return the list by head - - } - - // Method to print the LinkedList. - public static void printList(LinkedList list) - { - // Traverse through the LinkedList - - // Print the data at current node - - // Go to next node - } - - // Driver code - public static void main(String[] args) - { - /* Start with the empty list. */ - LinkedList list = new LinkedList(); - - // - // ******INSERTION****** - // - - // Insert the values - list = insert(list, 1); - list = insert(list, 2); - list = insert(list, 3); - list = insert(list, 4); - list = insert(list, 5); - - // Print the LinkedList - printList(list); - } -} \ No newline at end of file diff --git a/LinkedList.java b/LinkedList.java new file mode 100644 index 000000000..a0ca32035 --- /dev/null +++ b/LinkedList.java @@ -0,0 +1,94 @@ +// Java program to implement +// a Singly Linked List + +// Time Complexity : O(n) to add element to the end of the LL +// Space Complexity : O(n) +// Did this code successfully run on Leetcode : +// Any problem you faced while coding this: No + +public class LinkedList { + + Node head; // head of list + + // Linked list Node. + // This inner class is made static + // so that main() can access it + static class Node { + + int data; + Node next; + + // Constructor + Node(int d) + { + //Write your code here + this.data = d; + this.next = null; + } + } + + // Method to insert a new node + public static LinkedList insert(LinkedList list, int data) + { + // Create a new node with given data + Node temp = new Node(data); + + // If the Linked List is empty, + // then make the new node as head + if(list.head == null){ + list.head = temp; + return list; + } + + // Else traverse till the last node + // and insert the new_node there + Node pointer = list.head; + while(pointer.next != null){ + pointer = pointer.next; + } + + // Insert the new_node at last node + pointer.next = temp; + // Return the list by head + return list; + + } + + // Method to print the LinkedList. + public static void printList(LinkedList list) + { + // Traverse through the LinkedList + // if the list is empty + if(list.head == null){ + return; + } + Node pointer = list.head; + while(pointer != null){ + // Print the data at current node + System.out.println(pointer.data); + // Go to next node + pointer = pointer.next; + } + } + + // Driver code + public static void main(String[] args) + { + /* Start with the empty list. */ + LinkedList list = new LinkedList(); + + // + // ******INSERTION****** + // + + // Insert the values + list = insert(list, 1); + list = insert(list, 2); + list = insert(list, 3); + list = insert(list, 4); + list = insert(list, 5); + + // Print the LinkedList + printList(list); + } +} \ No newline at end of file diff --git a/Exercise_2.java b/StackAsLinkedList.java similarity index 51% rename from Exercise_2.java rename to StackAsLinkedList.java index 5a9c4868c..9d9b8f164 100644 --- a/Exercise_2.java +++ b/StackAsLinkedList.java @@ -1,52 +1,78 @@ -public class StackAsLinkedList { - - StackNode root; - - static class StackNode { - int data; - StackNode next; - - StackNode(int data) - { - //Constructor here - } - } - - - public boolean isEmpty() - { - //Write your code here for the condition if stack is empty. - } - - public void push(int data) - { - //Write code to push data to the stack. - } - - public int pop() - { - //If Stack Empty Return 0 and print "Stack Underflow" - //Write code to pop the topmost element of stack. - //Also return the popped element - } - - public int peek() - { - //Write code to just return the topmost element without removing it. - } - - //Driver code - public static void main(String[] args) - { - - StackAsLinkedList sll = new StackAsLinkedList(); - - sll.push(10); - sll.push(20); - sll.push(30); - - System.out.println(sll.pop() + " popped from stack"); - - System.out.println("Top element is " + sll.peek()); - } -} +// Time Complexity : O(1) for all operations +// Space Complexity : O(n) +// Did this code successfully run on Leetcode : +// Any problem you faced while coding this: No + +public class StackAsLinkedList { + + StackNode root; + + static class StackNode { + int data; + StackNode next; + + StackNode(int data) + { + //Constructor here + this.data = data; + } + } + + + public boolean isEmpty() + { + return root == null; + } + + public void push(int data) + { + StackNode temp = new StackNode(data); + if (root == null){ + root = temp; + } + else{ + temp.next = root; + root = temp; + } + } + + public int pop() + { + //If Stack Empty Return 0 and print "Stack Underflow" + //Write code to pop the topmost element of stack. + //Also return the popped element + if(root == null){ + System.out.println("Stack Underflow"); + return 0; + } + else{ + int poppedData = root.data; + root = root.next; + return poppedData; + } + } + + public int peek() + { + //Write code to just return the topmost element without removing it. + if(root == null){ + return 0; + } + else return root.data; + } + + //Driver code + public static void main(String[] args) + { + + StackAsLinkedList sll = new StackAsLinkedList(); + + sll.push(10); + sll.push(20); + sll.push(30); + + System.out.println(sll.pop() + " popped from stack"); + + System.out.println("Top element is " + sll.peek()); + } +}