LeetCode 面試題 04.04. 檢查平衡性 (雙重遞歸)

檢查平衡性

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    bool isBalanced(TreeNode* root) {
        if(!root) return true;
        return abs(getHeight(root->left)-getHeight(root->right))<=1 && 
        isBalanced(root->left) && isBalanced(root->right);
    }
    int getHeight(TreeNode* root){
        if(!root) return 0;
        return 1+max(getHeight(root->left),getHeight(root->right));
    }
};