1 #include <iostream>
2 using namespace std;
3
4 typedef long long ll;
5
6 const int maxn = 1010;
7
8 // 输入先序遍历和中序遍历， 求后序遍历；
9
10 int pre[maxn], in[maxn], post[maxn];
11 int k;
12
13 struct node
14 {
15 int value;
16 node *l, *r;
17 node(int value = 0, node *l = nullptr, node *r = nullptr):
18 value(value), l(l), r(r){}
19 };
20
21 void buildtree_dfs(int l, int r, int &t, node* &root)
22 {
23 int flag = -1;
24 for(int i = l; i <= r; i++)
25 {
26 if(in[i] == pre[t])
27 {
28 flag = i;
29 break;
30 }
31 }
32 if(flag == -1) return;
33 root = new node(in[flag]);
34 t++;
35 if(flag > l) buildtree_dfs(l, flag - 1, t, root->l);
36 if(flag < r) buildtree_dfs(flag + 1, r, t, root->r);
37 }
38
39 void preorder(node *root)
40 {
41 if(root != nullptr)
42 {
43 post[k++] = root->value;
44 preorder(root->l);
45 preorder(root->r);
46 }
47 }
48
49 void inorder(node *root)
50 {
51 if(root != nullptr)
52 {
53 inorder(root->l);
54 post[k++] = root->value;
55 inorder(root->r);
56 }
57 }
58
59 void postorder(node *root)
60 {
61 if(root != nullptr)
62 {
63 postorder(root->l);
64 postorder(root->r);
65 post[k++] = root->value;
66 }
67 }
68
69 int main()
70 {
71 int n;
72 while(cin >> n)
73 {
74 for(int i = 1; i <= n; i++) cin >> pre[i];
75 for(int i = 1; i <= n; i++) cin >> in[i];
76 node *root;
77 int t = 1;
78 buildtree_dfs(1, n, t, root);
79 k = 0;
80 postorder(root);
81 for(int i = 0; i < k; i++)
82 {
83 cout << post[i];
84 if(i != k - 1) cout << " ";
85 }
86 cout << endl;
87 }
88 return 0;
89 }
