蓝桥杯练习—对称字符串

 #define _CRT_SECURE_NO_WARNINGS 1 
#include<stdio.h>
#include<string.h>

char res[500000];

int main()
{
	int n;
	scanf("%d", &n);
	int len = 0;
	for (int i = 1; i <= n; i++)
	{
		strcat(res + len + 1, res);
		res[len] = 'A' + i - 1;
		len = strlen(res);
	}
	printf("%s\n", res);
	return 0;
}