题目

binary-tree-preorder-traversal

算法

* 直接模拟

代码

class Solution {

public:

    vector<int> preorderTraversal(TreeNode *root) {

        vector<int> res;

        stack<TreeNode*> s;

        if (!root) return res;

        s.push(root);

        while (!s.empty()) {

            TreeNode *p = s.top();

            res.push_back(p->val);

            s.pop();

            if (p->right) s.push(p->right);

            if (p->left) s.push(p->left);

        }

        return res;

    }

};