105 lines
3.4 KiB
Java
105 lines
3.4 KiB
Java
//<p>给你一棵二叉树的根节点 <code>root</code> ，找出并返回满足要求的节点数，要求节点的值等于其 <strong>子树</strong> 中值的 <strong>平均值</strong> 。</p>
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//
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//<p><strong>注意：</strong></p>
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//
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//<ul>
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// <li><code>n</code> 个元素的平均值可以由 <code>n</code> 个元素 <strong>求和</strong> 然后再除以 <code>n</code> ，并 <strong>向下舍入</strong> 到最近的整数。</li>
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// <li><code>root</code> 的 <strong>子树</strong> 由 <code>root</code> 和它的所有后代组成。</li>
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//</ul>
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//
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//<p> </p>
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//
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//<p><strong>示例 1：</strong></p>
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//<img src="https://assets.leetcode.com/uploads/2022/03/15/image-20220315203925-1.png" style="width: 300px; height: 212px;">
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//<pre><strong>输入：</strong>root = [4,8,5,0,1,null,6]
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//<strong>输出：</strong>5
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//<strong>解释：</strong>
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//对值为 4 的节点：子树的平均值 (4 + 8 + 5 + 0 + 1 + 6) / 6 = 24 / 6 = 4 。
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//对值为 5 的节点：子树的平均值 (5 + 6) / 2 = 11 / 2 = 5 。
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//对值为 0 的节点：子树的平均值 0 / 1 = 0 。
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//对值为 1 的节点：子树的平均值 1 / 1 = 1 。
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//对值为 6 的节点：子树的平均值 6 / 1 = 6 。
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//</pre>
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//
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//<p><strong>示例 2：</strong></p>
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//<img src="https://assets.leetcode.com/uploads/2022/03/26/image-20220326133920-1.png" style="width: 80px; height: 76px;">
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//<pre><strong>输入：</strong>root = [1]
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//<strong>输出：</strong>1
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//<strong>解释：</strong>对值为 1 的节点：子树的平均值 1 / 1 = 1。
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//</pre>
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//
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//<p> </p>
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//
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//<p><strong>提示：</strong></p>
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//
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//<ul>
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// <li>树中节点数目在范围 <code>[1, 1000]</code> 内</li>
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// <li><code>0 <= Node.val <= 1000</code></li>
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//</ul>
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//<div><li>👍 8</li><li>👎 0</li></div>
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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.LinkedList;
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import java.util.Queue;
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// 2265:统计值等于子树平均值的节点数
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public class CountNodesEqualToAverageOfSubtree {
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public static void main(String[] args) {
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Solution solution = new CountNodesEqualToAverageOfSubtree().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 int averageOfSubtree(TreeNode root) {
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counts(root);
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sums(root);
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return count;
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}
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Queue<Integer> queue = new LinkedList<>();
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int count = 0;
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private int counts(TreeNode root) {
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if (root == null) {
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return 0;
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}
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int cnt = counts(root.left) + counts(root.right) + 1;
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queue.add(cnt);
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return cnt;
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}
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private int sums(TreeNode root) {
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if (root == null) {
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return 0;
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}
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int sum = root.val;
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sum += sums(root.left);
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sum += sums(root.right);
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if (sum / queue.poll() == root.val) {
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count++;
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}
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return sum;
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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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