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LeetCodeSharp/Problems/Solution25.cs

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+// [25] Reverse Nodes in k-Group
+
+using LeetCodeSharp.Utils;
+
+namespace LeetCodeSharp.Problems25
+{
+    // Submission codes start here
+
+    /**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     public int val;
+ *     public ListNode next;
+ *     public ListNode(int val=0, ListNode next=null) {
+ *         this.val = val;
+ *         this.next = next;
+ *     }
+ * }
+ */
+    public class Solution
+    {
+        public ListNode ReverseKGroup(ListNode head, int k)
+        {
+            var dummyNode = new ListNode(-1)
+            {
+                next = head
+            };
+
+            var precursor = dummyNode;
+            var node = dummyNode.next;
+
+            while (node != null)
+            {
+                var current = node;
+                var n = current;
+                var count = 0;
+
+                // 先遍历一下看看够不够k个
+                while (n != null)
+                {
+                    count += 1;
+                    n = n.next;
+
+                    if (count == k)
+                    {
+                        break;
+                    }
+                }
+
+                if (count == k)
+                {
+                    node = n;
+                }
+                else
+                {
+                    break;
+                }
+
+                for (var i = 0; i < k - 1; i++)
+                {
+                    var next = current.next;
+
+                    current.next = next.next;
+                    next.next = precursor.next;
+                    precursor.next = next;
+                }
+
+                precursor = current;
+            }
+
+            return dummyNode.next;
+        }
+    }
+
+    // Submission codes end here
+}