晴问

#include <iostream>
#include <vector>
#include <queue>
#include <unordered_map>

using namespace std;

struct TreeNode {
    int data;
    TreeNode *left;
    TreeNode *right;

    TreeNode(int data) : data(data), left(nullptr), right(nullptr) {}
};

// 函数用于根据层序和中序遍历结果重建二叉树
TreeNode* buildTree(vector<int>& levelOrder, vector<int>& inOrder, int inStart, int inEnd, int levelStart, int levelEnd) {
    if (inStart > inEnd) return nullptr;

    TreeNode* root = new TreeNode(levelOrder[levelStart]);

    int inRootIndex = inStart;
    while (inOrder[inRootIndex] != levelOrder[levelStart]) {
        inRootIndex++;
    }

    int leftTreeSize = inRootIndex - inStart;

    root->left = buildTree(levelOrder, inOrder, inStart, inRootIndex - 1, levelStart + 1, levelStart + leftTreeSize);
    root->right = buildTree(levelOrder, inOrder, inRootIndex + 1, inEnd, levelStart + leftTreeSize + 1, levelEnd);

    return root;
}

// 先序遍历函数
void preOrder(TreeNode* root) {
    if (root == nullptr) return;
    cout << root->data << " ";
    preOrder(root->left);
    preOrder(root->right);
}

int main() {
    int n;
    cin >> n;
    vector<int> levelOrder(n), inOrder(n);

    for (int i = 0; i < n; ++i) {
        cin >> levelOrder[i];
    }
    for (int i = 0; i < n; ++i) {
        cin >> inOrder[i];
    }

    TreeNode* root = buildTree(levelOrder, inOrder, 0, n - 1, 0, n - 1);
    preOrder(root);

    return 0;
}