一定要注意，外部變數【陣列】開的大小，太大了會溢位，太小了提交的時候會溢位，這是一門學問啊

#include <iostream>
#include <vector>
#include <string>
#include <queue>
#include <cstring>

#define MAX 99999
using namespace std;

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

    tree()
    {
        left 
 
= NULL;
        right = NULL;
    }
};

tree *root;
int layerr[MAX];
int midd[MAX];
int nn;

tree *build(int *layer, int *mid, int n)
{
    if (n == 0)
        return NULL;
    int Llayer[MAX],Rlayer[MAX];
    int Lmid[MAX],Rmid[MAX];
    tree *t = new tree();
    t->data = layer[0];
    int x = 0;
    
 
while (layer[0] != mid[x])
        x++;
    //mid
    int c = 0;
    for (int i = 0; i < x; i++)
    {
        Lmid[c++] = mid[i];
    }
    c=0;
    for (int i = x+1; i < n; i++)
    {
        Rmid[c++] = mid[i];
    }
    //layer
    int Ll=0,Rl=0;
    for (int i = 1; i < n; i++)
    {
        for (int
 
 k = 0; k < x; k++)
        {
            if(layer[i] == mid[k])
                Llayer[Ll++] = mid[k];
        }
    }
    for (int i = 1; i < n; i++)
    {
        for (int k = x; k < n; k++)
        {
            if(layer[i] == mid[k])
                Rlayer[Rl++] = mid[k];
        }
    }
    t->left = build(Llayer, Lmid, Ll);
    t->right = build(Rlayer, Rmid, Rl);
    return t;
}

void PreOrder(tree *t)
{
    if (t)
    {
        cout << t->data << " ";
        PreOrder(t->left);
        PreOrder(t->right);

    }
}

void PostOrder(tree *t)
{
    if (t)
    {
        PostOrder(t->left);
        PostOrder(t->right);
        cout << t->data << " ";
    }
}

int main()
{
    cin >> nn;
    for (int i = 0; i < nn; ++i)
        cin >> layerr[i];
    for (int i = 0; i < nn; ++i)
        cin >> midd[i];
    root = build(layerr, midd, nn);
    PreOrder(root);
    cout << endl;
    PostOrder(root);
    return 0;
}

！