题解 | #二叉树的最大深度#

使用栈来实现

/*
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};
*/
class Solution {
public:
    vector<vector<int> > Print(TreeNode* pRoot) {
        if(pRoot == nullptr){
            return {};
        }
        
        stack<TreeNode*> st;
        vector<vector<int>> res;
        int flag = 1;
        st.push(pRoot);
        
        while(!st.empty()){
            int cur_size = st.size();
            vector<int> cur_res;
            stack<TreeNode*> temp;
            for(int i=0; i<cur_size; i++){
                auto node = st.top();
                st.pop();
                cur_res.push_back(node->val);
                if(flag){
                    if(node->left) temp.push(node->left);
                    if(node->right) temp.push(node->right);
                }
                else{
                    if(node->right) temp.push(node->right);
                    if(node->left) temp.push(node->left);
                }
            }
            st = temp;
            flag = !flag;
            res.push_back(cur_res);
        }
        return res;
    }
    
};