蓝桥杯--对称字符串

C++语言代码

#include <stdio.h>
#include <string.h>
char res[5000000];
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
", res);
    return 0;
}