写出非递归的方法实现对给定二叉树的先序和层序遍历算法,并给出一组数据

非递归的先序遍历算法：

void preOrder(TreeNode* root) {
    if (root == nullptr) return;
    stack<TreeNode*> stk;
    stk.push(root);
    while (!stk.empty()) {
        TreeNode* cur = stk.top();
        stk.pop();
        cout << cur->val << " ";
        if (cur->right != nullptr) stk.push(cur->right);
        if (cur->left != nullptr) stk.push(cur->left);
    }
}

非递归的层序遍历算法：

void levelOrder(TreeNode* root) {
    if (root == nullptr) return;
    queue<TreeNode*> q;
    q.push(root);
    while (!q.empty()) {
        int size = q.size();
        for (int i = 0; i < size; i++) {
            TreeNode* cur = q.front();
            q.pop();
            cout << cur->val << " ";
            if (cur->left != nullptr) q.push(cur->left);
            if (cur->right != nullptr) q.push(cur->right);
        }
    }
}

数据：

TreeNode* root = new TreeNode(1);
root->left = new TreeNode(2);
root->right = new TreeNode(3);
root->left->left = new TreeNode(4);
root->left->right = new TreeNode(5);
root->right->left = new TreeNode(6);
root->right->right = new TreeNode(7);

先序遍历输出：1 2 4 5 3 6 7

层序遍历输出：1 2 3 4 5 6 7