Commit 0f5d221

committed

Add implementations for cycle detection in linked lists, stack reversal, and pushing elements to the bottom of a stack

1 parent 23f114b commit 0f5d221Copy full SHA for 0f5d221

File tree

+156

-0

lines changed

+156

-0

lines changed

Lines changed: 51 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,51 @@`
	`1`	`+class ListNode {`
	`2`	`+ int val;`
	`3`	`+ ListNode next;`
	`4`	`+ ListNode(int x) {`
	`5`	`+ val = x;`
	`6`	`+ next = null;`
	`7`	`+ }`
	`8`	`+}`
	`9`	`+`
	`10`	`+public class CycleLinkedList {`
	`11`	`+ public boolean hasCycle(ListNode head) {`
	`12`	`+`
	`13`	`+ if(head == null){`
	`14`	`+ return false;`
	`15`	`+ }`
	`16`	`+ ListNode fast = head;`
	`17`	`+ ListNode slow = head;`
	`18`	`+`
	`19`	`+ while(fast != null && fast.next !=null){`
	`20`	`+ fast = fast.next.next;`
	`21`	`+ slow = slow.next;`
	`22`	`+`
	`23`	`+ if(fast == slow){`
	`24`	`+ return true;`
	`25`	`+ }`
	`26`	`+ }`
	`27`	`+ return false; // Added missing semicolon`
	`28`	`+ }`
	`29`	`+`
	`30`	`+ // Optional: Main method for testing`
	`31`	`+ public static void main(String[] args) {`
	`32`	`+ CycleLinkedList solution = new CycleLinkedList();`
	`33`	`+`
	`34`	`+ // Test case 1: No cycle`
	`35`	`+ ListNode head1 = new ListNode(1);`
	`36`	`+ head1.next = new ListNode(2);`
	`37`	`+ head1.next.next = new ListNode(3);`
	`38`	`+ head1.next.next.next = new ListNode(4);`
	`39`	`+`
	`40`	`+ System.out.println("Has cycle: " + solution.hasCycle(head1)); // false`
	`41`	`+`
	`42`	`+ // Test case 2: With cycle`
	`43`	`+ ListNode head2 = new ListNode(3);`
	`44`	`+ head2.next = new ListNode(2);`
	`45`	`+ head2.next.next = new ListNode(0);`
	`46`	`+ head2.next.next.next = new ListNode(-4);`
	`47`	`+ head2.next.next.next.next = head2.next; // Creates cycle`
	`48`	`+`
	`49`	`+ System.out.println("Has cycle: " + solution.hasCycle(head2)); // true`
	`50`	`+ }`
	`51`	`+}`

Lines changed: 33 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,33 @@`
	`1`	`+import java.util.Stack;`
	`2`	`+`
	`3`	`+public class ExampleOne {`
	`4`	`+ public static void main(String[] args) {`
	`5`	`+ Stack<Integer> list = new Stack<>();`
	`6`	`+`
	`7`	`+ //push operation`
	`8`	`+`
	`9`	`+ list.push(10);`
	`10`	`+ list.push(20);`
	`11`	`+ list.push(30);`
	`12`	`+ list.push(40);`
	`13`	`+ list.push(50);`
	`14`	`+`
	`15`	`+ System.out.println(list);`
	`16`	`+ System.out.println(list.peek());`
	`17`	`+`
	`18`	`+ //pop operation`
	`19`	`+`
	`20`	`+ list.pop();`
	`21`	`+ list.pop();`
	`22`	`+`
	`23`	`+ System.out.println("After Pop operations " + list);`
	`24`	`+`
	`25`	`+`
	`26`	`+ boolean isEmpty = list.isEmpty();`
	`27`	`+ if(isEmpty){`
	`28`	`+ System.out.println("Yes stack is Empty ");`
	`29`	`+ }else{`
	`30`	`+ System.out.println("No , Stack is not Empty ");`
	`31`	`+ }`
	`32`	`+ }`
	`33`	`+}`

Lines changed: 30 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,30 @@`
	`1`	`+import java.util.Stack;`
	`2`	`+`
	`3`	`+public class PushAtButtomProblem {`
	`4`	`+ public static void main(String[] args) {`
	`5`	`+ Stack<Integer> list = new Stack<>();`
	`6`	`+ list.push(10);`
	`7`	`+ list.push(20);`
	`8`	`+ list.push(30);`
	`9`	`+ list.push(40);`
	`10`	`+`
	`11`	`+ System.out.println("Atfirst the stack is : " +list);`
	`12`	`+`
	`13`	`+ PushAtButtom(list, 100);`
	`14`	`+`
	`15`	`+ System.out.println("After add the Element at the Buttom: " + list);`
	`16`	`+`
	`17`	`+ }`
	`18`	`+`
	`19`	`+ static void PushAtButtom(Stack<Integer> list,int element){`
	`20`	`+ //base case`
	`21`	`+ if(list.isEmpty()){`
	`22`	`+ list.push(element);`
	`23`	`+ return;`
	`24`	`+ }`
	`25`	`+`
	`26`	`+ int top = list.pop();`
	`27`	`+ PushAtButtom(list, element);`
	`28`	`+ list.push(top);`
	`29`	`+ }`
	`30`	`+}`

Lines changed: 42 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,42 @@`
	`1`	`+import java.util.Stack;`
	`2`	`+`
	`3`	`+public class ReverseStack {`
	`4`	`+ public static void main(String[] args) {`
	`5`	`+ Stack<Integer> list = new Stack<>();`
	`6`	`+ list.push(10);`
	`7`	`+ list.push(20);`
	`8`	`+ list.push(30);`
	`9`	`+ list.push(40);`
	`10`	`+`
	`11`	`+ System.out.println("Before Reverse : " +list);`
	`12`	`+`
	`13`	`+ reverse(list);`
	`14`	`+ System.out.println("After Reverse: " +list);`
	`15`	`+`
	`16`	`+`
	`17`	`+`
	`18`	`+ }`
	`19`	`+`
	`20`	`+ static void PushAtButtom(Stack<Integer> list, int element) {`
	`21`	`+ // base case`
	`22`	`+ if (list.isEmpty()) {`
	`23`	`+ list.push(element);`
	`24`	`+ return;`
	`25`	`+ }`
	`26`	`+`
	`27`	`+ int top = list.pop();`
	`28`	`+ PushAtButtom(list, element);`
	`29`	`+ list.push(top);`
	`30`	`+ }`
	`31`	`+`
	`32`	`+ static void reverse(Stack<Integer> list){`
	`33`	`+ if(list.isEmpty()){`
	`34`	`+ return;`
	`35`	`+ }`
	`36`	`+`
	`37`	`+ int top = list.pop();`
	`38`	`+ reverse(list);`
	`39`	`+ PushAtButtom(list, top);`
	`40`	`+`
	`41`	`+ }`
	`42`	`+}`

Comments

(0)