add

5.leetcode/src/com/fanxb/common/Q25.java

@@ -45,12 +45,82 @@ public class Q25 {
         }
     }
 
+    public ListNode newReverseKGroup(ListNode head, int k) {
+        if (k == 1) return head;
+        boolean firstDeal = true;
+        int count = 0;
+        ListNode res = head, left = null, right, lastRight = null;
+        while (head != null) {
+            if (left == null) left = head;
+            count++;
+            if (count == k) {
+                right = head;
+                reverse(left, right);
+                if (firstDeal) {
+                    res = right;
+                    firstDeal = false;
+                } else {
+                    lastRight.next = right;
+                }
+                lastRight = left;
+                head = left.next;
+                left = null;
+                count = 0;
+            } else {
+                head = head.next;
+            }
+        }
+        return res;
+    }
+
+    private void reverse(ListNode start, ListNode end) {
+        ListNode last = start, current = start.next, next, temp = end.next;
+        while (current != null && current != temp) {
+            next = current.next;
+            current.next = last;
+            last = current;
+            current = next;
+        }
+        start.next = temp;
+    }
+
+
+    public ListNode new1ReverseKGroup(ListNode head, int k) {
+        ListNode res = new ListNode(0);
+        res.next = head;
+        ListNode pre = res, next;
+        while (head != null) {
+            ListNode end = head;
+            for (int i = 0; i < k - 1 && end != null; i++) end = end.next;
+            if (end == null) break;
+            next = end.next;
+            end.next = null;
+            pre.next = end;
+            reverse1(head);
+            head.next = next;
+            pre = head;
+            head = head.next;
+        }
+        return res.next;
+    }
+
+    public ListNode reverse1(ListNode head) {
+        ListNode pre = head, cur = head.next, next;
+        while (cur != null) {
+            next = cur.next;
+            cur.next = pre;
+            pre = cur;
+            cur = next;
+        }
+        return pre;
+    }
+
     public static void main(String[] args) {
         ListNode node = new ListNode(1);
         node.next = new ListNode(2);
         node.next.next = new ListNode(3);
         node.next.next.next = new ListNode(4);
         node.next.next.next.next = new ListNode(5);
-        new Q25().reverseKGroup(node, 3);
+        new Q25().new1ReverseKGroup(node, 2);
     }
 }