[数据结构与算法]110.平衡二叉树

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    int maxHeight(TreeNode* root)
    {
        if(!root)
        {
            return 0;
        }

        int l_height=maxHeight(root->left);
        int r_height=maxHeight(root->right);

        return ((l_height>r_height)?(l_height+1):(r_height+1));
    }

    bool isBalanced(TreeNode* root) {
        if(!root)
        {
            return true;
        }

        if(abs(maxHeight(root->left)-maxHeight(root->right))<=1)//(maxHeight(root->left)==maxHeight(root->right)||maxHeight(root->left)==maxHeight(root->right)+1||maxHeight(root->left)==maxHeight(root->right)-1)
        {
            return isBalanced(root->left)*isBalanced(root->right);
        }
        
        return false;
    }
};