Create 092.Reverse-Linked-List-II_v2.cpp

Author: wisdompeak

Linked_List/092.Reverse-Linked-List-II/092.Reverse-Linked-List-II_v2.cpp

@@ -0,0 +1,55 @@
+/**
+ * Definition for singly-linked list.
+ * struct ListNode {
+ * int val;
+ * ListNode *next;
+ * ListNode() : val(0), next(nullptr) {}
+ * ListNode(int x) : val(x), next(nullptr) {}
+ * ListNode(int x, ListNode *next) : val(x), next(next) {}
+ * };
+ */
+class Solution {
+public:
+ ListNode* reverseBetween(ListNode* head, int left, int right) 
+ {
+ ListNode* dummy = new ListNode(0);
+ dummy->next = head;
+
+ ListNode* p = dummy;
+ for (int i=0; i<right; i++)
+ p = p->next;
+ ListNode* c = p->next;
+ p->next = NULL;
+
+ p = dummy;
+ for (int i=0; i<left-1; i++)
+ p = p->next;
+ ListNode* b = p->next;
+ p->next = NULL;
+
+ b = reverseLinkedList(b);
+
+ p = dummy;
+ while (p->next) p = p->next;
+ p->next = b;
+ while (p->next) p = p->next;
+ p->next = c;
+
+ return dummy->next;
+ }
+
+ ListNode* reverseLinkedList(ListNode* h)
+ {
+ ListNode* last = NULL;
+ ListNode* cur = h;
+ ListNode* nxt;
+ while (cur)
+ {
+ nxt = cur->next;
+ cur->next = last;
+ last = cur;
+ cur = nxt;
+ }
+ return last;
+ }
+};