1 #include <iostream>
2 #include <vector>
3 #include <algorithm>
4 #include <queue>
5 #include <stack>
6 #include <string>
7 #include <fstream>
8 #include <map>
9 using namespace std;
10
11 struct node {
12 int data;
13 struct node *left, *right;
14 node() : data(0), left(NULL), right(NULL) { }
15 node(int d) : data(d), left(NULL), right(NULL) { }
16 };
17
18 void prints(node *root) {
19 if (!root) return;
20 prints(root->left);
21 cout << root->data << " ";
22 prints(root->right);
23 }
24
25 node *_buildtree(int pre[], int post[], int &preindex, int l, int h, int size) {
26 if (preindex >= size || l > h) return NULL;
27 node *root = new node(pre[preindex++]);
28 if (l == h) return root;
29 int i = l;
30 for (; i <= h; i++) if (pre[preindex] == post[i]) break;
31 if (i <= h) {
32 root->left = _buildtree(pre, post, preindex, l, i, size);
33 root->right = _buildtree(pre, post, preindex, i+1, h, size);
34 }
35 return root;
36 }
37
38 node *buildtree(int pre[], int post[], int size) {
39 int preindex = 0;
40 return _buildtree(pre, post, preindex, 0, size-1, size);
41 }
42
43 int main() {
44 int pre[9] = {1, 2, 4, 8, 9, 5, 3, 6, 7};
45 int post[9] = {8, 9, 4, 5, 2, 6, 7, 3, 1};
46 node *root = buildtree(pre, post, 9);
47 prints(root);
48 return 0;
49 }
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