//输入某二叉树的前序遍历和中序遍历的结果，请重建出该二叉树。假设输入的前序遍历和中序遍历的结果中都不含重复的数字。
//例如输入前序遍历序列{1,2,4,7,3,5,6,8}和中序遍历序列{4,7,2,1,5,3,8,6}，则重建二叉树并返回。
1 作者：技术不宅
2 链接：https://www.nowcoder.com/questionTerminal/8a19cbe657394eeaac2f6ea9b0f6fcf6
3 来源：牛客网
4
5 #include <iostream>
6 #include <vector>
7 using namespace std;
8
9
10 struct TreeNode {
11 int val;
12 TreeNode *left;
13 TreeNode *right;
14 TreeNode(int x) : val(x), left(NULL), right(NULL) {}
15 };
16
17 struct TreeNode* reConstructBinaryTree(vector<int> pre, vector<int> in)
18 {
19 if (pre.size() == NULL)
20 return NULL;
21 TreeNode* root = new TreeNode(pre[0]);
22 int i;
23 for (i = 0; i < in.size() && in[i] != pre[0]; i++);
24 vector<int> pre_left, in_left,pre_right,in_right;
25 int pre_i = 1;
26 for (int j = 0; j < in.size(); j++)
27 {
28 if (j < i)
29 {
30 in_left.push_back(in[j]);
31 pre_left.push_back(pre[pre_i]);
32 pre_i++;
33 }
34 else if (j>i)
35 {
36 in_right.push_back(in[j]);
37 pre_right.push_back(pre[pre_i]);
38 pre_i++;
39 }
40 }
41 root->left = reConstructBinaryTree(pre_left, in_left);
42 root->right = reConstructBinaryTree(pre_right, in_right);
43 return root;
44 }
45
46 int main()
47 {
48 vector<int> pre = { 1, 2, 4, 7, 3, 5, 6, 8 };
49 vector<int> in = { 4, 7, 2, 1, 5, 3, 8, 6 };
50 TreeNode* root= reConstructBinaryTree(pre, in);
51 int a = 0;
52 }