数据结构——已知先序中序求后序，已知中序后序求先序

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <algorithm>
 5 #include <malloc.h>
 6 #include <string>
 7 #include <vector>
 8 #include <stack>
 9 #include <queue>
10 #include <set>
11 #include <map>
12 
13 #define FRER() freopen("in.txt", "r", stdin);
14 
15 using namespace std;
16 
17 //函数状态码定义
18 #define TRUE        1
19 #define FALSE       0
20 #define OK          1
21 #define ERROR       0
22 #define INFEASIBLE -1
23 #define OVERFLOW   -2
24 
25 typedef char TElemType;
26 typedef int Status;
27 
28 typedef struct BiNode {
29     TElemType data;
30     struct BiNode *lchild, *rchild;
31 }BiNode, *BiTree;
32 
33 BiTree BinaryTreeFormorderings(char *, char *, int);
34 BiTree BinaryTreePostorderings(char *, char *, int);
35 
36 /*
37 ABDECFG
38 DBEAFCG
39 DEBFGCA
40 */
41 
42 int main()
43 {
44     FRER()
45     int n;
46     char str[100], ptr[100];
47     cin >> n >> str >> ptr;
48     BinaryTreePostorderings(str, ptr, n);
49     return 0;
50 }
51 
52 BiTree BinaryTreeFormorderings(char *pre, char *in, int len) {
53     if(len <= 0)
54         return NULL;
55     BiNode *node = new BiNode;
56     node->data = *pre;
57     int idx = 0;
58     while(idx < len) {
59         if(*(in + idx) == *pre)
60             break;
61         ++idx;
62     }
63     node->lchild = BinaryTreeFormorderings(pre + 1, in, idx);
64     node->rchild = BinaryTreeFormorderings(pre + idx + 1, in + idx + 1, len - (idx + 1));
65     cout << node->data << ‘ ‘;
66     return node;
67 }
68 
69 BiTree BinaryTreePostorderings(char *in, char *post, int len) {
70     if(len == 0)
71         return NULL;
72     BiNode *node = new BiNode;
73     node->data = *(post + len - 1);
74     cout << node->data << ‘ ‘;
75     int idx = 0;
76     while(idx < len) {
77         if(*(in + idx) == *(post + len - 1))
78             break;
79         ++idx;
80     }
81     node->lchild = BinaryTreePostorderings(in, post, idx);
82     node->rchild = BinaryTreePostorderings(in + idx + 1, post + idx, len - (idx + 1));
83     return node;
84 }