剑指Offer，链表中环的入口点

zebinh · zebinh · commit f46c847a54cb · 2020-01-10T20:51:20.000+08:00
diff --git a/swordoffer/EntryNodeOfListSolution.java b/swordoffer/EntryNodeOfListSolution.java
@@ -0,0 +1,43 @@
+/**
+ * ��ָOffer�������л�����ڵ�
+ */
+
+
+ 
+public class ListNode {
+    int val;
+    ListNode next = null;
+
+    ListNode(int val) {
+        this.val = val;
+    }
+}
+
+ public class EntryNodeOfListSolution {
+
+    public ListNode EntryNodeOfLoop(ListNode pHead)
+    {
+        ListNode slow = pHead;
+        ListNode fast = pHead;
+        
+        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;
+        }
+
+        fast = pHead;
+        while(slow != fast) {
+            slow = slow.next;
+            fast = fast.next;
+        }
+
+        return slow;
+    }
+ }
