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by Sumit Chourasia | Oct 08, 2020 | Category :coding | Tags : algorithm binary-tree data-structure easy leetcode tree

Average of Levels in Binary Tree - Tree - Easy - LeetCode

Average of Levels in Binary Tree - Tree - Easy - LeetCode

Given a non-empty binary tree, return the average value of the nodes on each level in the form of an array.
Example 1:
Input:
    3
   / \
  9  20
    /  \
   15   7
Output: [3, 14.5, 11]
Explanation:
The average value of nodes on level 0 is 3,  on level 1 is 14.5, and on level 2 is 11. Hence return [3, 14.5, 11].
Note:
The range of node's value is in the range of 32-bit signed integer.

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left;
 *     public TreeNode right;
 *     public TreeNode(int val=0, TreeNode left=null, TreeNode right=null) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
public class Solution {
    public IList<double> AverageOfLevels(TreeNode root) {
        var res = new List<double>();
        var queue = new Queue<TreeNode>();
        queue.Enqueue(root);
        while(queue.Count()>0){
            int count = queue.Count();
            int i = count;
            double sum = 0;
            while(i-->0){
                var node = queue.Dequeue();
                sum += node.val;
                if(node.left != null){
                    queue.Enqueue(node.left);
                }
                if(node.right != null){
                    queue.Enqueue(node.right);
                }
            }
            res.Add(sum/count);
        }
        return res;
    }
}

Time Complexity: O(n)

Space Complexity: O(n)