Create 102. Binary Tree Level Order Traversal

Author: khushi3004

102. Binary Tree Level Order Traversal

@@ -0,0 +1,44 @@
+class Solution {
+    public List<List<Integer>> levelOrder(TreeNode root) {
+        List<List<Integer>> result = new ArrayList<>();
+        if(root == null) return result;
+        
+        Queue<TreeNode> q = new LinkedList<>();
+        q.offer(root);
+        
+        while(!q.isEmpty()) {
+            int size = q.size();
+            List<Integer> currLevel = new ArrayList<>();
+            while(size-- > 0) {
+                TreeNode curr = q.poll();
+                currLevel.add(curr.val);
+                if(curr.left != null) q.offer(curr.left);
+                if(curr.right != null) q.offer(curr.right);
+            }
+            result.add(currLevel);
+        }
+        return result;
+    }
+}
+
+class Solution {
+    List<List<Integer>> result;
+    public List<List<Integer>> levelOrder(TreeNode root) {
+        result = new ArrayList<>();
+        if(root ==null) return result;
+        traverse(root, 0);
+        return result;
+    }
+    
+    private void traverse(TreeNode node, int level) {
+        if(node == null) return;
+        if(result.size() == level){
+            result.add(new ArrayList<>());
+        }
+        
+        result.get(level).add(node.val);
+        traverse(node.left, level+1);
+        traverse(node.right, level+1);
+        
+    }
+}