lintcode 中等题：balanced binary tree 平衡二叉树

/**
 * Definition of TreeNode:
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left, right;
 *     public TreeNode(int val) {
 *         this.val = val;
 *         this.left = this.right = null;
 *     }
 * }
 */
public class Solution {
    /**
     * @param root: The root of binary tree.
     * @return: True if this Binary tree is Balanced, or false.
     */
    public boolean isBalanced(TreeNode root) {
        // write your code here
        if(root == null)
            return true;
        int lft = depth(root.left);
        int rit = depth(root.right);
        if(Math.abs(lft-rit)<=1){
            return isBalanced(root.left)&&isBalanced(root.right);
        }
        else
            return false;
        
    }
    public int depth(TreeNode root){
        if(root ==null)
            return 0;
        if(root.left==null && root.right ==null)
            return 1;
        int lft = depth(root.left);
        int rit = depth(root.right);
        return Math.max(lft,rit) + 1;
    }
}