【2001NOIP普及组】T3. 求先序排列 试题解析

1. #include<bits/stdc++.h>
2. using namespace std;
3. string a,b;
4. void build(int l1,int r1,int l2,int r2){
5.  int m=a.find(b[r2]);
6.  int n=b.find(b[r2]);
7.  cout<<b[r2];
8.  if(m>l1) build(l1,m-1,n-1,m-1);
9.  if(m<r2) build(m+1,r1,m,r2-1);
10. } 
11. void build(string mid,string back)
12. {
13.   int m = mid.find(back[back.size()-1]);
14.   cout<<back[back.size()-1];
15.   if(m>0) build(mid.substr(0,m),back.substr(0,m));
16.   if(m+1<mid.size()) build(mid.substr(m+1),back.substr(m,back.size()-m-1));
17. }
18. int main()
19. {
20.   cin>>a>>b;
21.   //build(0,a.size()-1,0,b.size()-1);
22.   build(a,b);
23.   return 0;
24. }