leetcode292周赛--6057. 统计值等于子树平均值的节点数

一:题目

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二:上码

/*** 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 {/**思路:1.用前序遍历统计结点个数 并将结点的val值装进容器2.用层序遍历遍历每个结点然 然后调用以该节点为根结点的前序遍历  计算结果*/public void preOrder(TreeNode root,List<Integer> list) {if (root == null) return ;list.add(root.val);preOrder(root.left,list);preOrder(root.right,list);}public int getAvg(List<Integer> list) {int sum = 0;for (Integer num:list) {sum += num;}return sum/list.size();}public int averageOfSubtree(TreeNode root) {int ans = 0;ArrayDeque<TreeNode> queue =  new ArrayDeque<>();if (root != null) queue.add(root);while (!queue.isEmpty()) {TreeNode node = queue.poll();List<Integer> list = new ArrayList<>();preOrder(node,list);int temp = getAvg(list);if (temp == node.val) ans++;if (node.left != null) queue.add(node.left);if (node.right != null) queue.add(node.right);}return ans;}
}