[Tree] [洛谷] P1030 求先序排列

先序：根左右
中序：左根右
后序：左右根

//#pragma GCC optimize(2)
#include <cstdio>
#include <iostream>
#include <cstdlib>
#include <cmath>
#include <cctype>
#include <string>
#include <cstring>
#include <algorithm>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <ctime>
#include <vector>
#include <fstream>
#include <list>
#include <iomanip>
#include <numeric>
using namespace std;
typedef long long ll;

const int MAXN = 1e6 + 10;

void find(string mid, string lst)
{
    if(lst.length() >= 1)
    {
        int len = lst.length();

        char ret = lst[len - 1];

        cout<<ret;

        string tmidl = "", tmidr = "", tlstl = "", tlstr = "";

        int pos = 0;

        for(;mid[pos] != ret; pos++);

        for(int i = 0; i < pos; i++)
            tmidl = tmidl + mid[i];
        
		for(int i = pos + 1; i < len; i++)
        	tmidr = tmidr + mid[i];
        	
        for(int i = 0; i < pos; i++)
       		tlstl = tlstl + lst[i];
       		
       	for(int i = pos; i < len - 1; i++)
       		tlstr = tlstr + lst[i];

        find(tmidl, tlstl);

        find(tmidr, tlstr);

    }
}

int main()
{
    ios::sync_with_stdio(false);

    cin.tie(0);     cout.tie(0);

    string mid, lst;
    
    cin>>mid>>lst;   

    find(mid, lst);

    return 0;
}