题目描述： 

代码实现：

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
int TreeHeight(struct TreeNode* root)
{
    if(root==NULL)
        return 0;
    //左右子树中大的那个+1
    int left=TreeHeight(root->left);
    int right=TreeHeight(root->right);
    return left>right?left+1:right+1;
}
bool isBalanced(struct TreeNode* root){
    if(root==NULL)
        return true;
    int left=TreeHeight(root->left);
    int right=TreeHeight(root->right);
    if(left-right>1||right-left>1)
    {
        return false;
    }
    return isBalanced(root->left)&&isBalanced(root->right);
}