ts-3: flatten list

Author: aikhelis

typescript/Linked Lists/flatten_multi_level_list.ts

@@ -0,0 +1,35 @@
+/* Definition of MultiLevelListNode:
+class MultieLevelListNode {
+    val: number; next: MLLNode; child: MLLNode;
+    constructor(val: number){
+        this.val = val;
+        this.next = null;
+        this.child = null;
+    }
+}
+type MLLNode = MultieLevelListNode | null;
+*/
+
+function flattenMultiLevelList(head: MLLNode): MLLNode {
+    if (!head) 
+        return head;
+    let tail: MLLNode = head;
+    // Find the tail of the linked list at the first level.
+    while (tail.next !== null)
+        tail = tail.next;
+    let curr: MLLNode = head;
+    // Process each node at the current level. If a node has a child linked list,
+    // append it to the tail and then update the tail to the end of the extended 
+    // linked list. Continue until all nodes at the current level are processed.
+    while (curr !== null){
+        if (curr.child !== null){
+            tail.next = curr.child;
+            // Disconnect the child linked list from the current node.
+            curr.child = null;
+            while (tail.next !== null)
+                tail = tail.next;
+        }
+        curr = curr.next;
+    }
+    return head;
+}