[Cup] Blue Bridge string BASIC-22 FJ

Subject description:

FJ in the sand table to write some string like this:
A1 = "A"
A2 = "ABA"
A3 = "ABACABA"
A4 = "ABACABADABACABA"
... ...
you can find out the rules and write them all columns AN it?

Enter a description:

Only a few: N ≤ 26.

Output Description:

Please output corresponding string AN, to a newline character. Output must not contain extra space or line feed, carriage return. 

Sample input:

3

Sample output:

ABACABA

Problem-solving ideas:

Recursive solution.

AC Code:

#include <bits/stdc++.h>
using namespace std;
#define Up(i,a,b) for(int i = a; i <= b; i++)

void fun(int n)
{
    if(n >= 1)
    {
        fun(n-1);   //前半部分
        printf("%c",'A'+n-1);
        fun(n-1);  //后半部分
    }
}

int main()
{
    int n;
    cin >> n;
    fun(n);
    return 0;
}