2

Author: kedebug

ReverseLinkedListII/ReverseLinkedListII.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 *reverseBetween(ListNode *head, int m, int n) {
+        // Start typing your C/C++ solution below
+        // DO NOT write int main() function
+        
+        ListNode prev_head(0);
+        prev_head.next = head;
+        ListNode *prev = &prev_head;
+        ListNode *current = head;
+              
+        for (int i = 0; i < m - 1; i++) {
+            prev = prev->next;
+            current = current->next;
+        }
+        ListNode *end = current;
+        for (int i = m - 1; i < n; i++) {
+            ListNode *next = current->next;
+            current->next = prev->next;
+            prev->next = current;
+            current = next;
+        }
+        end->next = current;
+        return prev_head.next;
+    }
+};