Create Binary_Tree_Level_Order_Traversal.java

Author: 17tanya

GraphsDFS&BFS/Binary_Tree_Level_Order_Traversal.java

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+//Leetcode 102. Binary Tree Level Order Traversal
+//Question - https://leetcode.com/problems/binary-tree-level-order-traversal/
+
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode(int x) { val = x; }
+ * }
+ */
+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<TreeNode>();
+        
+        TreeNode curr = null;
+        q.add(root);
+        
+        while(q.isEmpty()==false){
+            int nodesAtCurrLevel = q.size();
+            //System.out.println(nodesAtCurrLevel);
+            List<Integer> layer = new ArrayList<>();
+            for(int i = 0 ; i < nodesAtCurrLevel ; i++){
+                curr = q.poll();
+                layer.add(curr.val);
+                if(curr.left!=null) q.add(curr.left);
+                if(curr.right!=null) q.add(curr.right);
+            }
+            result.add(layer);
+        }
+        
+        return result;
+        
+    }
+}