142. Linked List Cycle II

Author: ChlZhYa

LeetCode/0142. Linked List Cycle II/src/Solution.java

@@ -0,0 +1,23 @@
+public class Solution {
+    public ListNode detectCycle(ListNode head) {
+        if(head == null){
+            return null;
+        }
+        ListNode slow = head,fast = head;
+        while(fast != null && fast.next != null){
+            slow = slow.next;
+
+            fast = fast.next.next;
+
+            if(slow == fast){
+                ListNode cur = head;
+                while(cur != slow){
+                    cur = cur.next;
+                    slow = slow.next;
+                }
+                return cur;
+            }
+        }
+        return null;
+    }
+}

LeetCode/0142. Linked List Cycle II/src/TestCase.java

@@ -0,0 +1,20 @@
+public class TestCase {
+
+    public static void main(String[] args) {
+//        ListNode listNode = new ListNode(3);
+//        ListNode listNode1 = new ListNode(2);
+//        ListNode listNode2 = new ListNode(0);
+//        ListNode listNode3 = new ListNode(-4);
+//        listNode.next = listNode1;
+//        listNode1.next = listNode2;
+//        listNode2.next = listNode3;
+//        listNode3.next = listNode1;
+        ListNode listNode = new ListNode(0);
+        ListNode listNode1 = new ListNode(0);
+        listNode1.next = listNode;
+        listNode.next = listNode1;
+        Solution solution = new Solution();
+        ListNode result = solution.detectCycle(listNode);
+        System.out.println(result.val);
+    }
+}