【树】 leetcode_110 _ 平衡二叉树

【树】 leetcode_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:
    bool isBalanced(TreeNode* root) {
        int re = get_height(root);
        return (re!=-1);
    }
    int get_height (TreeNode* cur){
        if (cur==nullptr){
            return 0;
        }
        
        int le_h = get_height(cur->left);
        if (le_h == -1) return -1;
        int ri_h = get_height(cur->right);
        if (ri_h == -1) return -1;
        if (abs(le_h-ri_h)>1){
            return -1;
        }
        else{
            int height = max(le_h, ri_h)+1;
            return height;
        }
    }
};