Time: 0 ms (100.00%), Space: 7.4 MB (59.91%) - LeetHub

Author: ComputerScientist-01

reverse-linked-list-ii/reverse-linked-list-ii.cpp

@@ -0,0 +1,46 @@
+/**
+ * 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) {
+        if(left==right)
+        {
+            return head;
+        }
+        
+        
+        ListNode* dummy = new ListNode();
+        dummy->next=head;
+        int i=0;
+        // if(head != NULL) 
+        // {
+        //     dummy->next=head;
+        // }
+        ListNode* pre=dummy;
+        for (i=0;i<left-1;++i) 
+        {
+            
+            pre=pre->next;
+        }
+        ListNode* curr = pre->next;
+        ListNode* cn=nullptr;
+        for (i=0;i<right-left;++i)
+        {
+            cn=curr->next;
+            curr->next=cn->next;
+            cn->next=pre->next;
+            pre->next=cn;
+        }
+        return dummy->next;
+    }
+};