c++代码

#include<iostream>
#include<cstring>
#include<algorithm>
#include<queue>
#include<unordered_map>

using namespace std;

const int N = 40;
int n;
int inorder[N], preorder[N];
unordered_map<int, int> l, r, pos;

int build(int il, int ir, int pl, int pr) {
    int root = preorder[pl];
    int k = pos[root];

    //镜像操作：
    //让原本的左子树变为右子树，右子树变为左子树
    if (il < k) r[root] = build(il, k - 1, pl + 1, pl + k - il);
    if (ir > k) l[root] = build(k + 1, ir, pl + k + 1 - il, pr);
    return root;
}

void bfs(int root) {
    queue<int> q;
    q.push(root);

    int u = 1;
    while (!q.empty()) {
        auto t = q.front();
        q.pop();
        if (l[t]) q.push(l[t]);
        if (r[t]) q.push(r[t]);
        if (u == 1) cout << t;
        else cout << " " << t;
        u++;
    }
}

int main() {
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> inorder[i];
        pos[inorder[i]] = i;
    }
    for (int i = 0; i < n; i++) cin >> preorder[i];

    int root = build(0, n - 1, 0, n - 1);
    bfs(root);

    return 0;
}