用尾递归求二叉树的maxDepth

function maxDepth(root) {
    return tailRecursiveMaxDepth(root, 0);
}

function tailRecursiveMaxDepth(node, currentDepth) {
    if (node === null) {
        return currentDepth;
    }
    const leftDepth = tailRecursiveMaxDepth(node.left, currentDepth + 1);
    const rightDepth = tailRecursiveMaxDepth(node.right, currentDepth + 1);
    return Math.max(leftDepth, rightDepth);
}

// 二叉树节点定义
class TreeNode {
    constructor(val, left = null, right = null) {
        this.val = val;
        this.left = left;
        this.right = right;
    }
}

// 示例用法
const root = new TreeNode(3, 
    new TreeNode(9), 
    new TreeNode(20, 
        new TreeNode(15), 
        new TreeNode(7)
    )
);

console.log(maxDepth(root)); // 输出: 3