判断一棵树是否是平衡二叉树

//判断一棵树是否是平衡二叉树
public class Main18 {

    public static void main(String[] args) {
        TreeNode tree = new TreeNode(1);
        tree.left = new TreeNode(2);
        tree.right = new TreeNode(3);
        tree.left.left = new TreeNode(4);
        tree.left.right = new TreeNode(5);
//        int deep = treeDeep(tree);
        System.out.println(isBalancedTree(tree));
    }

    //获取树的深度,采用递归的方式
    public static int treeDeep(TreeNode treeNode){
        if(treeNode == null) return 0;
        //左子树深度
        int leftDeep = treeDeep(treeNode.left);
        //右子树深度
        int rightDeep = treeDeep(treeNode.right);
        return Math.max(leftDeep+1,rightDeep+1);
    }

    //判断是否是平衡二叉树，即判断每个节点下的左子树与右子树的高度差的绝对值
    public static boolean isBalancedTree(TreeNode treeNode){
        if(treeNode == null) return true;
        //获得左子树的高度
        int leftChild = treeDeep(treeNode.left);
        int rightChild = treeDeep(treeNode.right);
        //高度差
        int dep = Math.abs(leftChild-rightChild);
        if(dep>1) return false;
        return isBalancedTree(treeNode.left)&&isBalancedTree(treeNode.right);
    }

}

class TreeNode{
    int val;
    TreeNode left;
    TreeNode right;
    public TreeNode(int val){
        this.val = val;
    }
}