题解 | #二叉树的深度#

> 一种是二叉树的后序遍历；
> 一种是队列，即广度遍历。
/*
struct TreeNode {
	int val;
	struct TreeNode *left;
	struct TreeNode *right;
	TreeNode(int x) :
			val(x), left(NULL), right(NULL) {
	}
};*/
class Solution {
public:
    int TreeDepth(TreeNode* pRoot) {
        if (!pRoot)
            return 0;
        int level = 0;
        queue<TreeNode* > q;
        q.push(pRoot);
        while (!q.empty()) {
            int sz = q.size();
            while(sz--) {
                TreeNode* p = q.front();
                q.pop();
                if (p->left)
                    q.push(p->left);
                if (p->right)
                    q.push(p->right);
            }
            level = level + 1;
        }
        return level;
    }
};
或
if (pRoot == nullptr) 
	return 0;   //递归的关键语句，即终止条件
	int llen = TreeDepth(pRoot->left);
    int rlen = TreeDepth(pRoot->right);
return max(llen, rlen) + 1;