Create Maximum Level Sum of a Binary Tree

Author: HarryWangATX

Maximum Level Sum of a Binary Tree

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+/**
+ * Definition for a binary tree node.
+ * 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;
+ *     }
+ * }
+ */
+class Solution {
+    Map<Integer, Integer> sums = new HashMap<>();
+    public int maxLevelSum(TreeNode root) {
+        helper(root, 1);
+        int max = Integer.MIN_VALUE;
+        int level = 0;
+        Iterator hmIterator = sums.entrySet().iterator(); 
+        while (hmIterator.hasNext()) { 
+            Map.Entry mapElement = (Map.Entry)hmIterator.next(); 
+            if((int)mapElement.getValue() > max){
+                max = (int)mapElement.getValue();
+                level = (int)mapElement.getKey();
+            } 
+        } 
+        return level;
+    }
+    public void helper(TreeNode root, int depth){
+        if(root == null){
+            return ;
+        }
+        sums.put(depth, sums.getOrDefault(depth, 0)+root.val);
+        helper(root.left, depth+1);
+        helper(root.right, depth+1);
+    }
+}