省选模拟赛 至危警告

分析：f(x)和x是相关联的，枚举其中一个，通过计算得到另一个，再判断时候合法即可. 因为f(x)最多只有81,枚举f(x)即可.

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>

using namespace std;
typedef long long ll;

const int maxn = 110;
int T;
ll a,b,c,k,ans,anss[maxn],tot;

ll check(ll x)
{
    ll res = 0;
    while (x)
    {
        res += x % 10;
        x /= 10;
    }
    return res;
}

ll qpow(ll a,ll b)
{
    ll res = 1;
    while (b)
    {
        if (b & 1)
            res *= a;
        a *= a;
        b >>= 1;
    }
    return res;
}

int main()
{
    //freopen("test.txt","r",stdin);
    //freopen("safe.out","w",stdout);
    scanf("%d",&T);
    while (T--)
    {
        ans = 0;
        tot = 0;
        scanf("%lld%lld%lld%lld",&a,&b,&c,&k);
        for (ll i = 0; i <= 81; i++)
        {
            ll temp = qpow(i,a) * b + c;
            if (temp >= 0 && temp <= k)
            {
                if (check(temp) == i)
                {
                    ans++;
                    anss[++tot] = temp;
                }
            }
        }
        if (ans == 0)
            printf("0
-1
");
        else
        {
            sort(anss + 1,anss + 1 + tot);
            printf("%lld
",ans);
            for (int i = 1; i <= tot; i++)
                printf("%lld ",anss[i]);
            printf("
");
        }
    }

    return 0;
}