Problem110.java

class Problem110 {

 public static void main(String[] args) {
 Problem110 p = new Problem110();
 TreeNode root = new TreeNode(1);
 root.left = new TreeNode(2);
 root.left.left = new TreeNode(3);
 root.left.left.left = new TreeNode(4);
 root.left.left.left.left = new TreeNode(5);
 System.out.println(p.isBalanced(root));
 }

 public boolean isBalanced(TreeNode root) {
 if (root == null) return true;

 int rightHeight = height(root.right);
 int leftHeight = height(root.left);

 if (rightHeight <0 || leftHeight <0) {
 return false;
 }

 if (Math.abs(leftHeight - rightHeight) <= 1) {
 return true;
 }
 
 return false;
 }

 int height(TreeNode root) {
 if (root == null) return 0;
 int leftHeight = height(root.left);
 int rightHeight = height(root.right);

 int err = Math.abs(leftHeight - rightHeight);
 if ( err > 1 || err < 0) {
 return Integer.MIN_VALUE;
 }
 int val = Math.max(leftHeight, rightHeight) + 1;
 return val;
 }
}