Create 0025-reverse-nodes-in-k-group.go

go/0025-reverse-nodes-in-k-group.go

@@ -0,0 +1,34 @@
+func reverseKGroup(head *ListNode, k int) *ListNode {
+    dummy := &ListNode{Val: 0, Next: head}
+    groupPrev := dummy
+
+    for true {
+        kth := getKth(groupPrev, k)
+        if kth == nil {
+            break;
+        }
+        groupNext := kth.Next
+
+        // reverse group
+        prev, curr := kth.Next, groupPrev.Next
+        for curr != groupNext {
+            tmp := curr.Next
+            curr.Next = prev
+            prev = curr
+            curr = tmp
+        }
+
+        tmp := groupPrev.Next
+        groupPrev.Next = kth
+        groupPrev = tmp
+    }
+    return dummy.Next
+}
+
+func getKth(curr *ListNode, k int) *ListNode {
+    for curr != nil && k > 0 {
+        curr = curr.Next
+        k -= 1
+    }
+    return curr
+}