note

Author: guangxush

guangxu/202101/20210117.md

@@ -80,23 +80,22 @@ class Solution {
             if(ss_prev==null)
                 break;
             ss=ss_prev.next;
-			ss_prev.next = null;
+			      ss_prev.next = null;
             ListNode[] arr = reverse(ff);
             if(ff_prev==null){
                 head=arr[0];
-            }
-			else{
+            }else{
                 ff_prev.next  = arr[0];
             }
             ff.next = ss;
-			ss_prev = arr[1];
-			ff_prev = ss_prev;
-			ff=ss;
+        		ss_prev = arr[1];
+        		ff_prev = ss_prev;
+        		ff=ss;
         }
         return head;
-    }
-
-    private ListNode[] reverse(ListNode head){
+      }
+      
+      private ListNode[] reverse(ListNode head){
         ListNode pre = head;
         ListNode now = head;
         while(now!=null){
@@ -110,6 +109,46 @@ class Solution {
 }
 ```
 
+
+```java
+class Solution {
+    public ListNode reverseKGroup(ListNode head, int k) {
+
+        //checking size
+        ListNode sizeNode = head;
+        int size = 0;
+        while(sizeNode!=null){
+            sizeNode= sizeNode.next;
+            size++;
+        }
+
+        if(head==null || head.next == null || size<k )
+            return head;
+
+        ListNode curr = head;
+        ListNode prev= null;
+        ListNode nextNode ;
+        int count = 0;
+
+        while(curr!=null && count < k) {
+            nextNode= curr.next;
+            curr.next = prev;
+            prev = curr;
+            curr = nextNode;
+            count++;
+        }
+
+        ListNode temp = prev;
+        while(temp.next!=null){
+            temp = temp.next;
+        }
+        temp.next = reverseKGroup(curr,k);
+        return prev;
+
+    }
+}
+```
+
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