110. Balanced Binary Tree.java

public class Solution {
    private boolean result=true;
    public boolean isBalanced(TreeNode root) {
        validate(root);
        return result;
    }
    public int validate(TreeNode root){
        if(root==null)
            return 0;
        int l=validate(root.left);
        int r=validate(root.right);
        if(Math.abs(l-r)>1)
            result=false;
        return 1+Math.max(l,r);
    }
}