95 lines
2.4 KiB
Java
95 lines
2.4 KiB
Java
//给定一个非空二叉树的根节点 root , 以数组的形式返回每一层节点的平均值。与实际答案相差 10⁻⁵ 以内的答案可以被接受。
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//
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//
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//
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// 示例 1：
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//
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//
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//
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//
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//输入：root = [3,9,20,null,null,15,7]
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//输出：[3.00000,14.50000,11.00000]
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//解释：第 0 层的平均值为 3,第 1 层的平均值为 14.5,第 2 层的平均值为 11 。
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//因此返回 [3, 14.5, 11] 。
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//
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//
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// 示例 2:
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//
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//
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//
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//
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//输入：root = [3,9,20,15,7]
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//输出：[3.00000,14.50000,11.00000]
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//
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//
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//
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//
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// 提示：
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//
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//
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//
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//
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// 树中节点数量在 [1, 10⁴] 范围内
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// -2³¹ <= Node.val <= 2³¹ - 1
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//
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// Related Topics 树 深度优先搜索 广度优先搜索 二叉树 👍 319 👎 0
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package leetcode.editor.cn;
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import com.code.leet.entiy.TreeNode;
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import java.util.ArrayList;
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import java.util.LinkedList;
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import java.util.List;
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import java.util.Queue;
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//637:二叉树的层平均值
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public class AverageOfLevelsInBinaryTree {
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public static void main(String[] args) {
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Solution solution = new AverageOfLevelsInBinaryTree().new Solution();
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// TO TEST
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}
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//leetcode submit region begin(Prohibit modification and deletion)
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/**
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* Definition for a binary tree node.
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* public class TreeNode {
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* int val;
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* TreeNode left;
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* TreeNode right;
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* TreeNode() {}
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* TreeNode(int val) { this.val = val; }
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* TreeNode(int val, TreeNode left, TreeNode right) {
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* this.val = val;
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* this.left = left;
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* this.right = right;
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* }
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* }
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*/
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class Solution {
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public List<Double> averageOfLevels(TreeNode root) {
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Queue<TreeNode> queue = new LinkedList<>();
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queue.add(root);
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List<Double> result = new ArrayList<>();
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while (!queue.isEmpty()) {
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int size = queue.size();
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double sum = 0f;
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for (int i = 0; i < size; i++) {
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TreeNode node = queue.poll();
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if (node.left != null) {
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queue.add(node.left);
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}
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if (node.right != null) {
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queue.add(node.right);
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}
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sum += node.val;
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}
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result.add(sum / size);
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}
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return result;
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}
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}
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//leetcode submit region end(Prohibit modification and deletion)
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}
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