先序遍历加中序遍历确定后序遍历 

 1 #define bug(x) cout<<#x<<" is "<<x<<endl
 2 #define IO std::ios::sync_with_stdio(0)
 3 #include <bits/stdc++.h>
 4 using namespace  std;
 5 #define ll long long
 6 #define pb push_back
 7 const ll mod=1e9+7;
 8 const int N=2e5+10;
 9 
10 char s[N],t[N];
11 
12 struct node{
13     int c;
14     node *lson,*rson;
15 };
16 
17 int a[200],b[200],id[200],d[200],n,cnt;
18 
19 node *root;
20 
21 node* build(node *now){
22     now =new node();
23     //now=(node *)malloc(sizeof(node));
24     //now->lson=now->rson=NULL;
25     int k=id[s[cnt]];  
26     d[k]=1;
27     now->c=s[cnt++];
28     
29     if(k>1&&!d[k-1]){
30         now->lson=build(now->lson);
31     }
32     if(k<n&&!d[k+1]){
33         now->rson=build(now->rson);
34     }
35     return now;
36 }
37 
38 void preorder(node *now){
39     if(now->lson!=NULL)preorder(now->lson);
40     if(now->rson!=NULL)preorder(now->rson);
41     printf("%c",now->c);
42 }
43 
44 void work(){
45     preorder(build(root));
46 }
47 
48 int main(){
49     scanf("%s",s+1);
50     scanf("%s",t+1);
51     n=strlen(s+1);
52 
53     for(int i=1;i<=n;i++){
54         id[t[i]]=i;
55     }
56     work();
57 }
58 /*
59 ABCD
60 BADC
61 BDCA
62 
63 1 2 4 5 3 6
64 4 2 5 1 6 3
65 4 5 2 6 3 1
66 */

 

posted @ 2020-07-21 15:32  Venux  阅读(215)  评论(0)    收藏  举报