Balanced Binary Tree - 平衡树

• 如题：
  Given a binary tree, determine if it is height-balanced.
  For this problem, 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.
  平衡树的定义就是对于每一个节点，他的两棵子树的深度之差不能大于1

• 思路：
  这道题算的上是比较简单的了，思路大概就是两层：

  1. 递归判断每个节点
  2. 具体判断是每个节点的两个子树的深度比较

• 解题：

    bool isBalanced(TreeNode* root) {
        TreeNode *tempTreeNode = root;
        if (tempTreeNode == NULL) {
            return true;
        }
        if (abs(getMaxDeepth(tempTreeNode->left) - getMaxDeepth(tempTreeNode->right)) > 1) {
            return false;
        }
        return isBalanced(tempTreeNode->left) && isBalanced(tempTreeNode->right);
    }
    
    int getMaxDeepth(TreeNode *treeNode) {
        if (treeNode == NULL) {
            return 0;
        }
        int left = getMaxDeepth(treeNode->left);
        int right = getMaxDeepth(treeNode->right);
        return (left > right ? left : right) + 1;
    }