Create 0023-merge-k-sorted-lists.go

go/0023-merge-k-sorted-lists.go

@@ -0,0 +1,42 @@
+func mergeKLists(lists []*ListNode) *ListNode {
+    if lists == nil || len(lists) == 0 {
+        return nil
+    }
+
+    for len(lists) > 1 {
+        var mergedLists []*ListNode
+        for i := 0; i < len(lists); i += 2 {
+            l1 := lists[i]
+            var l2 *ListNode
+            if (i + 1) < len(lists) {
+                l2 = lists[i + 1]
+            }
+            mergedLists = append(mergedLists, mergeList(l1, l2))
+        }
+        lists = mergedLists
+    }
+    return lists[0]
+}
+
+func mergeList(l1, l2 *ListNode) *ListNode {
+    dummy := &ListNode{}
+    tail := dummy
+
+    for l1 != nil && l2 != nil {
+        if l1.Val < l2.Val {
+            tail.Next = l1
+            l1 = l1.Next
+        } else {
+            tail.Next = l2
+            l2 = l2.Next
+        }
+        tail = tail.Next
+    }
+    if l1 != nil {
+        tail.Next = l1
+    }
+    if l2 != nil {
+        tail.Next = l2
+    }
+    return dummy.Next
+}