3

Author: kedebug

RemoveDuplicatesfromSortedListII/RemoveDuplicatesfromSortedListII.cpp

@@ -0,0 +1,56 @@
+/**
+ * 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
+        
+        if (head == NULL)
+            return head;
+        
+        ListNode preHead(0);
+        preHead.next = head;
+        
+        ListNode *preprev = &preHead;
+        ListNode *prev = head;
+        ListNode *node = head->next;
+        bool flag = false;
+        
+        while (node != NULL) {
+            if (prev->val == node->val) {
+                ListNode *del = node;
+                node = node->next;
+                flag = true;
+                delete del;
+            }
+            else {
+                if (flag) {
+                    flag = false;
+                    preprev->next = node;
+                    prev = node;
+                    node = node->next;
+                } 
+                else {
+                    preprev = prev;
+                    prev = node;
+                    node = node->next;
+                }
+            }
+        }
+        if (flag) {
+            preprev->next = NULL;
+            delete prev;
+        }
+        
+        return preHead.next;
+    }
+};
+
+// Accepted after my first commit, yeah.