Completed LinkedList-1

DetectCycle.java

@@ -0,0 +1,41 @@
+// Time Complexity :O(n) (n amount and c is umber of coins )
+// Space Complexity :0(1)
+// Did this code successfully run on Leetcode : yes
+// Any problem you faced while coding this : nothing
+
+import java.util.LinkedList;
+import java.util.Queue;
+
+public class DetectCycle {
+    public class ListNode {
+        int val;
+        ListNode next;
+        ListNode() {}
+        ListNode(int val) { this.val = val; }
+        ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+    }
+
+    public ListNode detectCycle(ListNode head) {
+        ListNode slow = head;
+        ListNode fast = head;
+        boolean flag =true;
+
+        while(fast != null && fast.next != null){
+            slow = slow.next;
+            fast = fast.next.next;
+
+            if(slow == fast){
+                flag = false;
+                break;
+            }
+        }
+        if(flag) return null;
+        slow = head;
+        while(slow != fast){
+            slow = slow.next;
+            fast= fast.next;
+        }
+
+        return slow;
+    }
+}

RemoveNthNode.java

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+// Time Complexity :O(n)
+// Space Complexity :0(1)
+// Did this code successfully run on Leetcode : yes
+// Any problem you faced while coding this : nothing
+
+
+
+public class RemoveNthNode {
+    public class ListNode {
+        int val;
+        ListNode next;
+        ListNode() {}
+        ListNode(int val) { this.val = val; }
+        ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+    }
+
+    public ListNode removeNthFromEnd(ListNode head, int n) {
+        ListNode dummy = new ListNode(-1);
+        dummy.next=head;
+        int count =0; ListNode slow = dummy; ListNode fast=dummy;
+
+        while(count<=n){
+            fast = fast.next;
+            count++;
+        }
+
+        while(fast != null){
+            slow = slow.next;
+            fast = fast.next;
+        }
+
+        ListNode temp = slow.next;
+        slow.next = slow.next.next;
+        temp = null;
+
+        return dummy.next;
+    }
+}

ReverseLinkedList.java

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+// Time Complexity :O(n)
+// Space Complexity :0(1)
+// Did this code successfully run on Leetcode : yes
+// Any problem you faced while coding this : nothing
+
+public class ReverseLinkedList {
+      public class ListNode {
+        int val;
+        ListNode next;
+        ListNode() {}
+        ListNode(int val) { this.val = val; }
+        ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+    }
+
+    public ListNode reverseList(ListNode head) {
+       if(head == null){
+           return null;
+       }
+
+       ListNode prev = null;
+       ListNode curr = head;
+
+       while(curr != null){
+           ListNode temp = curr.next;
+           curr.next = prev;
+           prev = curr;
+           curr = temp;
+       }
+
+       return prev;
+    }
+}