1 #include <iostream>
2
3 using namespace std;
4
5 struct Node
6 {
7 Node(int v):value(v),left(NULL), right(NULL){}
8 struct Node * left;
9 struct Node * right;
10 int value;
11 };
12 int length;
13 Node * BuildTree(int * preorder, int * inorder, int * pos, int start, int end)
14 {
15 if((*pos) >= length) return NULL;
16 //if(start >= end) return NULL;
17 Node * root = new Node(preorder[*pos]);
18 int i;
19 for(i = start; i < end; ++i)
20 if(inorder[i] == preorder[*pos])
21 break;
22 //if(i == end) return NULL;
23
24 if(i > start)
25 {
26 *pos = *pos + 1;
27 root->left = BuildTree(preorder, inorder, pos, start, i);
28 }
29 if(end > i+1)
30 {
31 *pos = *pos + 1;
32 root->right = BuildTree(preorder, inorder, pos, i+1, end);
33 }
34 return root;
35
36 }
37 void InorderOutput(Node * root)
38 {
39 if(NULL == root) return;
40 InorderOutput(root->left);
41 cout << root->value << " ";
42 InorderOutput(root->right);
43 }
44 void FreeTree(Node * root)
45 {
46 if(NULL == root) return;
47 FreeTree(root->left);
48 FreeTree(root->right);
49 delete root;
50 }
51 int main()
52 {
53 int n;
54 while(cin >> n)
55 {
56 length = n;
57 int * preorder = new int[n];
58 int * inorder = new int[n];
59 for(int i = 0; i < n; ++i)
60 cin >> preorder[i];
61 for(int j = 0; j < n; ++j)
62 cin >> inorder[j];
63 int k = 0;
64 Node * root = BuildTree(preorder, inorder, &k, 0, n);
65 InorderOutput(root);
66 cout << endl;
67 // if(isTree)
68 // cout << "Yes" << endl;
69 // else cout << "NO" << endl;
70 delete preorder;
71 delete inorder;
72 FreeTree(root);
73 }
74 return 0;
75 }
