【剑指offer】二叉树的深度_solution1

题目：输入一棵二叉树，求该树的深度。从根结点到叶结点依次经过的结点（含根、叶结点）形成树的一条路径，最长路径的长度为树的深度。

 

/*
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};*/
class Solution {
public:
    int Max = -1;
    int TreeDepth(TreeNode* pRoot)
    {
        preOrder(pRoot,0);
        return Max;
    }
    void preOrder(TreeNode *r,int depth) {
        if (r == NULL) {
            if (depth > Max)
                Max = depth;
            return;
        }
        preOrder(r->left, depth + 1);
        preOrder(r->right, depth + 1);
    }
};