Create Remove Duplicates from Sorted List II.cpp

Author: daizhenyang

Remove Duplicates from Sorted List II.cpp

@@ -0,0 +1,34 @@
+/**
+ * Definition for singly-linked list.
+ * struct ListNode {
+ *     int val;
+ *     ListNode *next;
+ *     ListNode(int x) : val(x), next(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    ListNode *deleteDuplicates(ListNode *head) {
+        // Start typing your C/C++ solution below
+        // DO NOT write int main() function
+        ListNode *h=NULL,*t=NULL;
+        if (!head)return NULL;
+        ListNode *ptr=head,*pre=NULL;
+        while (ptr)
+        {
+            if ((!pre||pre->val!=ptr->val)&&(!ptr->next||ptr->next->val!=ptr->val))
+            {
+                if (!h)h=t=ptr;
+                else 
+                {
+                    t->next=ptr;
+                    t=ptr;
+                }
+            }
+            pre=ptr;
+            ptr=ptr->next;
+        }
+        if (t)t->next=NULL;  //forgot if (t)
+        return h;
+    }
+};