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Author: 10coder

AverageOfLevelsBT.java

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+//https://leetcode.com/problems/average-of-levels-in-binary-tree/
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Queue;
+
+public class AverageOfLevelsBT {
+
+//    public class TreeNode {
+//        int val;
+//        TreeNode left;
+//        TreeNode right;
+//        TreeNode() {}
+//        TreeNode(int val) { this.val = val; }
+//        TreeNode(int val, TreeNode left, TreeNode right) {
+//            this.val = val;
+//            this.left = left;
+//            this.right = right;
+//        }
+//    }
+
+//We can use BFS having a count of level size with number of elements in the queue and travesing only till that cnt
+    public List<Double> averageOfLevels(TreeNode root) {
+        List<Double> res  = new ArrayList<>();
+        Queue<TreeNode> q = new LinkedList<>();
+        if(root==null) {
+            return res;
+        }
+        q.add(root);
+        while(!q.isEmpty()) {
+            int levelSize=q.size();
+            double avg=0,cnt=0;
+            for(int i=0;i<levelSize;i++) {
+                TreeNode tn=q.poll();
+                if(tn.left!=null) {
+                    q.add(tn.left);
+                }
+                if(tn.right!=null) {
+                    q.add(tn.right);
+                }
+                avg+=(double)(tn.val);
+            }
+            avg/=levelSize;
+            res.add(avg);
+        }
+        return res;
+    }
+}