REVERSE NODES IN A LINKED LIST IN K GROUPS

Linkedlist/reverse k nodes in ll.CPP

@@ -0,0 +1,69 @@
+/**
+ * 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*reverse(ListNode*head, ListNode*tail) {
+        if (head == tail)
+            return head;
+        ListNode * temp = reverse(head->next, tail);
+        ListNode*loc = head->next;
+        loc->next = head;
+
+        head->next = NULL;
+        return temp;
+
+    }
+    ListNode* reverseKGroup(ListNode* head, int k) {
+        if (k == 1)
+            return head;
+
+        ListNode*templ = head;
+        ListNode*tail = NULL;
+        int c = 1;
+        while (templ != NULL) {
+            int j = k - 1;
+            ListNode*temp = templ;
+            while (j && temp->next != NULL) {
+                temp = temp->next;
+                j--;
+
+            }
+            if (temp->next == NULL && j > 0) {
+                tail->next = templ;
+                cout << 1;
+                break;
+            }
+
+            ListNode*temp1 = temp->next;
+            ListNode*temp2 = reverse(templ, temp);
+            templ = temp1;
+            ListNode*temp3 = temp2;
+            while (temp3->next != NULL) {
+                temp3 = temp3->next;
+            }
+            temp3->next = temp1;
+            if (c != 1) {
+
+                tail->next = temp2;
+                tail = temp3;
+            }
+            if (c == 1) {
+                head = temp2;
+            }
+            c++;
+            tail = temp3;
+        }
+        return head;
+
+
+
+    }
+};