[bzoj4292] [PA2015]Równanie

Posted 2020-07-26

　　枚举f(n)...检验一下f(f(n)*k)是否等于枚举的值。

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<cstring>
 4 #include<algorithm>
 5 #define ll long long
 6 using namespace std;
 7 const int maxn=50233;
 8 int i,ans;
 9 ll a,b,k;
10  
11 int ra;char rx;
12 inline int read(){
13     rx=getchar(),ra=0;
14     while(rx<‘0‘||rx>‘9‘)rx=getchar();
15     while(rx>=‘0‘&&rx<=‘9‘)ra*=10,ra+=rx-48,rx=getchar();return ra;
16 }
17  
18 inline int get(ll x){
19     int sm=0;
20     while(x)sm+=(x%10)*(x%10),x/=10;
21     return sm;
22 }
23 int main(){
24     scanf("%lld%lld%lld",&k,&a,&b);ll num=k;
25     for(i=1;i<=1458&&num<=b;i++,num+=k)
26         if(num>=a&&get(num)==i)ans++;
27     printf("%d\\n",ans);
28 }

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