Leetcode110. 平衡二叉树

题目传送：​​https://leetcode.cn/problems/balanced-binary-tree/​​

运行效率

代码如下：

class Solution {
     public boolean isBalanced(TreeNode root) {
        //处理特殊情况
        //处理边界情况
        if (root == null) {
            return true;
        }
        //1、首先要确保左右子树的高度差不能超过1
        //获取左子树的高度
        int leftHeight = getHeight(root.left);
        //获取右子树的高度
        int rightHeight = getHeight(root.right);
        if (Math.abs(leftHeight - rightHeight) > 1) {
            return false;
        }
        //递归去判断左右两个子树都平衡
        boolean leftBalanced = isBalanced(root.left);
        boolean rightBalanced = isBalanced(root.right);
        return leftBalanced && rightBalanced;
    }
    

    /**
     * 获取树的高度
     *
     * @param root
     * @return
     */
    public int getHeight(TreeNode root) {
        //处理边界情况
        if (root == null) {
            return 0;
        }
        if (root.left == null && root.right == null) {
            return 1;
        }
        //获取左子树的高度
        int leftHeight = getHeight(root.left);
        //获取右子树的高度
        int rightHeight = getHeight(root.right);
        return Math.max(leftHeight, rightHeight) + 1;
    }
}