题目

这个题和树的遍历那题一个思路，唯一改变的地方就是这里要求要先镜像二叉树，所以这里在递归时，先从右子树开始进入递归函数（将build函数上下调换位置）即可。

代码

#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>

using namespace std;

const int N = 35;
int pre[N], in[N], p[N];
vector<int> level[N];

/* 
void build (int prel, int prer, int inl, int inr, int d)
{
    if (prel > prer) return;
    int val = pre[prel];
    level[d].push_back(val);
    int k = p[val];
    build(prel + 1, prel + k - 1 - inl, inl, k - 1, d + 1);
    build(prel + k - inl, prer, k + 1, inr, d + 1);
}
*/

void build (int prel, int prer, int inl, int inr, int d)
{
    if (prel > prer) return;
    int val = pre[prel];
    level[d].push_back(val);
    int k = p[val];
    build(prel + k - inl + 1, prer, k + 1, inr, d + 1);
    build(prel + 1, prel + k - inl, inl, k - 1, d + 1);

}

int main()
{
    int n;
    cin >> n;
    for (int i = 0; i < n; i ++ ) cin >> in[i];
    for (int i = 0; i < n; i ++ ) cin >> pre[i];

    for (int i = 0; i < n; i ++ ) p[in[i]] = i;

    build(0, n - 1, 0, n - 1, 0);

    bool flag = false;
    for (int i = 0; i < n; i ++ )
    {
        if (!flag)
        {
            for (int x : level[i])
                cout << x;
            flag = true;
        }
        else 
        {
            for (int x : level[i])
                cout << ' ' << x;
        }
    }
    return 0;
}