Given a binary tree. Determine if it is height-balanced. A height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1.

Definition of a tree:

// Java
class TreeNode
{
public:
  int val;
  TreeNode left;
  TreeNode right;
  TreeNode(int x) {
    val = x;
    left = NULL; 
    right = NULL;
};

// C++
class TreeNode
{
public:
  int val;
  TreeNode *left;
  TreeNode *right;
  TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};

Implement function isBalanced that returns true if the tree is balanced and false otherwise.

// Java
boolean isBalanced(TreeNode tree)

// C++
bool isBalanced(TreeNode *tree)

Example

Function isBalanced returns true because tree is balanced.