add cpp solution

Author: zouwx2cs

solution/0092.Reverse Linked List II/Solution.cpp

@@ -0,0 +1,40 @@
+/**
+ * Definition for singly-linked list.
+ * struct ListNode {
+ *     int val;
+ *     ListNode *next;
+ *     ListNode(int x) : val(x), next(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    ListNode* reverseBetween(ListNode* head, int m, int n) {
+        ListNode headNode(0) ;
+        headNode.next = head ;
+        
+        n = n-m+1 ;
+        
+        ListNode *p = &headNode ;
+        while (--m) // 移动m-1次，故--m
+            p = p->next ;
+        
+        ListNode revNode(0) ;
+        ListNode *pRev = &revNode ;
+        pRev->next = nullptr ;
+        ListNode *pN = p->next ;
+        
+        ListNode *pTmp ;
+        while (n--)
+        {
+            pTmp = p->next ;
+            p->next = p->next->next ;
+            pTmp->next = pRev->next ;
+            pRev->next = pTmp ;
+        }
+        
+        pN->next = p->next ;
+        p->next = revNode.next ;
+        
+        return headNode.next ;
+    }
+};