题解

#include<cstdio>
#include<cstdlib>
#include<cstring>
const int N=100;
int n,m;
int a[N];
char sa[10]={'A','B','C','D','E','F','G','H','I','J'};
int main()
{
    scanf("%d%d",&n,&m);
    int tot=0;
    while(n!=0)
    {
        a[++tot]=n%m;
        n/=m;
        if(a[tot]<0) a[tot]-=m,n++;
    }
    for(int i=tot;i>=1;i--)
    {
        if(a[i]<10) printf("%d",a[i]);
        else printf("%c",sa[a[i]-10]);
    }
}