牛客练习赛104 B 114514

https://ac.nowcoder.com/acm/contest/43058/B

思路

要求1~n满足如下式子的个数

\((i^{11}-i)(i^{451}-i^4)\equiv(i^{11}-i^4)(i^{11}-i)(mod 451*4)\)

打表可知，全都符合条件，所以输出n就行

代码

#include<algorithm>
#include<iostream>
#include<cstring>
#include<cstdio>
#include<cctype>
#include<bitset>
#define ll long long
#define gc getchar
#define maxn 10005
#define mo 1804
using namespace std;

inline ll read(){
	ll a=0;int f=0;char p=gc();
	while(!isdigit(p)){f|=p=='-';p=gc();}
	while(isdigit(p)){a=(a<<3)+(a<<1)+(p^48);p=gc();}
	return f?-a:a;
}int n;

inline int kuai(int a,int k){
	int p=1;
	while(k){
		if(k&1)p=p*a%mo;
		a=a*a%mo;k>>=1;
	}
	return p;
}
inline bool pan(int x){
	return ((kuai(x,451)-kuai(x,4))%mo+mo)%mo==((kuai(x,11)-kuai(x,4))%mo+mo)%mo;
}

int main(){
	n=read();
	cout<<n<<endl;
	/*for(int i=1;i<=n;++i){
		printf("%d  %d\n",i,pan(i));
	}*/
	return 0;
}