获得树的深度（深度优先遍历）（递归）

思想

1. 先获得左右子树的最大深度
2. 比较左右子树的最大深度
3. 返回当前子树最大深度+1的值

代码

int GetTreeDepth(TreeNode* node){
        if(!node){
            return 0;
        }
        int left = GetTreeDepth(node->left);
        int right = GetTreeDepth(node->right);
        
        //return (left >= right ? left : right) + 1;
        return max(left,right) + 1;
    }

经典 leetcode 例题

检查树的平衡性
https://leetcode-cn.com/problems/check-balance-lcci/

class Solution {
public:
    bool isBalanced(TreeNode* root) {
        if(root == NULL)
            return true;

        int left = GetTreeDepth(root->left);
        int right = GetTreeDepth(root->right);
        int result = abs(left - right);
        return result < 2 && isBalanced(root->left) && isBalanced(root->right); 
    }

    int GetTreeDepth(TreeNode* node){
        if(!node){
            return 0;
        }
        int left = GetTreeDepth(node->left);
        int right = GetTreeDepth(node->right);
        
        //return (left >= right ? left : right) + 1;
        return max(left,right) + 1;
    }
};