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package com.leetcode;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
public class AverageLevelsBinaryTree {
//https://leetcode.com/problems/average-of-levels-in-binary-tree/
//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 {
public List averageOfLevels(TreeNode root) {
List result = new LinkedList();
if(root == null) return result;
Queue queue = new LinkedList();
queue.offer(root);
while(queue.size() > 0){
Queue values = new LinkedList();
LinkedList level = new LinkedList();
while(queue.size() > 0){
TreeNode node = queue.poll();
values.add(node.val);
if(node.left != null)
level.add(node.left);
if(node.right != null)
level.add(node.right);
}
long num = 0;
long den = 0;
while(values.size() > 0){
num += values.poll();
den += 1;
}
Double average = (double) num/den;
queue = level;
result.add(average);
}
return result;
}
}
}
// Optimized
class SolutionOptimized {
public List averageOfLevels(TreeNode root) {
Queue queue = new LinkedList();
List result = new LinkedList();
queue.offer(root);
while(queue.size() > 0){
int size = queue.size();
long levelNum = 0;
long levelDen = size;
while(size > 0){
TreeNode node = queue.poll();
levelNum += node.val;
size--;
if(node.left != null){
queue.offer(node.left);
}
if(node.right != null){
queue.offer(node.right);
}
}
Double avg = (double) levelNum/levelDen;
result.add(avg);
}
return result;
}
}