LeetCode.515. 在每个树行中找最大值

LeetCode.515. 在每个树行中找最大值

 BFS

/**
 * 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<Integer> largestValues(TreeNode root) {
        List<Integer> ansList = new ArrayList<>();
        if (root == null) {
            return ansList;
        }
        Queue<TreeNode> queue = new LinkedList<>();
        queue.offer(root);
        while (!queue.isEmpty()) {
            int size = queue.size();
            int max = Integer.MIN_VALUE;
            for (int i = 0; i < size; i++) {
                TreeNode node = queue.poll();
                max = Math.max(max, node.val);
                if (node.left != null) {
                    queue.offer(node.left);
                }
                if (node.right != null) {
                    queue.offer(node.right);
                }
            }
            ansList.add(max);
        }
        return ansList;
    }
}

复杂度分析：

• 时间复杂度：O(n)，每个元素进队出队各一次
• 空间复杂度：O(n)

标签：node,queue,right,TreeNode,val,int,最大值,LeetCode.515,树行
来源： https://blog.csdn.net/weixin_45867071/article/details/122751347