[LeetCode] Average of Levels in Binary Tree

>>문제설명

leetcode.com/problems/average-of-levels-in-binary-tree/

Average of Levels in Binary Tree - LeetCode

>mySolution

class Solution {
    public double getAverage(LinkedList<TreeNode> linkedList){
        long sum = 0;
        for(TreeNode treeNode : linkedList){
            sum += treeNode.val;
        }
        return (double)sum / linkedList.size();
    }

    public List<Double> averageOfLevels(TreeNode root) {
        LinkedList<TreeNode> linkedList = new LinkedList<>();
        LinkedList<TreeNode> nextList = new LinkedList<>();
        List<Double> answerList = new ArrayList<>();
        linkedList.add(root);

        while (!linkedList.isEmpty()){
            answerList.add(getAverage(linkedList));
            nextList.clear();
            while (!linkedList.isEmpty()){
                TreeNode treeNode = linkedList.poll();
                if(treeNode.left != null) nextList.add(treeNode.left);
                if(treeNode.right != null) nextList.add(treeNode.right);
            }
            linkedList.addAll(nextList);
        }

        return answerList;
    }
}

> Result

 

> Modify

class Solution {
    public List<Double> averageOfLevels(TreeNode root) {
        LinkedList<TreeNode> linkedList = new LinkedList<>();
        List<Double> answerList = new ArrayList<>();
        linkedList.add(root);
        long sum;
        int size;

        while (!linkedList.isEmpty()){
            sum = 0;
            size = linkedList.size();
            for(int idx = 0; idx < size; idx++){
                TreeNode treeNode = linkedList.poll();
                sum += treeNode.val;
                if(treeNode.left != null) linkedList.addLast(treeNode.left);
                if(treeNode.right != null) linkedList.addLast(treeNode.right);
            }
            answerList.add((double)sum / size);
        }
        return answerList;
    }
}

 

>Result

 

leetCode 엔진 자체가 같은 코드를 넣어도 결과가 다르게 나온다는 점을 알았다.