0513. Find Bottom Left Tree Value #

题目 #

给定一棵二叉树的 根节点 root，找出该二叉树的 最底层 最左边 节点的值。

假定二叉树至少有一个节点。

思路 #

层数遍历

代码 #

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 int findBottomLeftValue(TreeNode root) {
        int ans = root.val;
        
        Queue<TreeNode> queue = new Linkedlist<>();
        queue.offer(root);
        while (queue.size() != 0) {
            int layerSize = queue.size();
            ans = queue.peek().val;
            for (int i = 0; i < layerSize; i++) {
                TreeNode node = queue.poll();
                if (node.left != null) queue.offer(node.left);
                if (node.right != null) queue.offer(node.right);
            }
        }
        
        return ans;
    }
}