两种题解(但大致一样)

1.int转char

#include<bits/stdc++.h>
#define int long long
using namespace std;
signed main()
{
    int n;
    cin>>n;
    for(int i=0;i<26;i++)
    {
        int x=i+n;
        x%=26;
        cout<<char(x+'A');
    }
    return 0;
}

2.打表

#include<bits/stdc++.h>
#define int long long
using namespace std;
char a[30]={0,'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
signed main()
{
    int n;
    cin>>n;
    for(int i=0;i<26;i++)
    {
        cout<<a[(i+n)%26+1];
    }
    return 0;
}