已知中序和前序序列建二叉树

 1 #include<iostream>
 2 using namespace std;
 3 
 4 struct BinaryTreeNode
 5 {
 6     int m_nValue;
 7     BinaryTreeNode * m_pLeft;
 8     BinaryTreeNode * m_pRight;
 9     //int tag;
10 };
11 int foreOrder[8] = {1, 2, 4, 7, 3, 5, 6, 8};
12 int inOrder[8] = {4, 7, 2, 1, 5, 3, 8, 6};
13 int length = 8;
14 BinaryTreeNode * buildTree( int * i, int first, int last)
15 {
16     if((*i) >= length) return NULL;
17     int j;
18     for(j = 0; j < length; j++)
19         if(inOrder[j] == foreOrder[*i])
20             break;
21     BinaryTreeNode * root = (BinaryTreeNode *)malloc(sizeof(BinaryTreeNode));
22     root->m_nValue = foreOrder[*i];
23     root->m_pLeft = NULL;
24     root->m_pRight = NULL;
25     *i += 1;
26     if(j > first)
27         root->m_pLeft = buildTree(i, first, j);
28     if(last > j+1)
29         root->m_pRight = buildTree(i, j+1, last);
30     return root;
31 }
32 //中序遍历
33 void inOrderOutput(BinaryTreeNode * root)
34 {
35     if(root == NULL) return;
36     inOrderOutput(root->m_pLeft);
37     printf("%d ", root->m_nValue);
38     inOrderOutput(root->m_pRight);
39 }
40 int main()
41 {
42     int i = 0;
43     BinaryTreeNode * root = buildTree(&i, 0, length);
44     inOrderOutput(root);
45     return 0;
46 }