Create 0142-linked-list-cycle-ii.java

Author: Tetsuya3850

java/0142-linked-list-cycle-ii.java

@@ -0,0 +1,24 @@
+public class Solution {
+    public ListNode detectCycle(ListNode head) {
+        ListNode slow = head;
+        ListNode fast = head;
+        while (fast != null && fast.next != null) {
+            slow = slow.next;
+            fast = fast.next.next;
+            if (slow == fast) {
+                break;
+            }
+        }
+
+        if (fast == null || fast.next == null) {
+            return null;
+        }
+
+        ListNode slow2 = head;
+        while (slow != slow2) {
+            slow = slow.next;
+            slow2 = slow2.next;
+        }
+        return slow;
+    }
+}