https://www.cnblogs.com/njczy2010/p/3930688.html
https://blog.csdn.net/dominating413421391/article/details/44203019?locationNum=1&fps=1
https://blog.csdn.net/piekey1994/article/details/38436511 [数学]
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
int len;
int n = 1000;
int next[10000];
int f[50000];
char s[50000];
int Pow(int a, int b)
{
int res=1;
while(b)
{
if(b&1)
res=res*a%7;
a=a*a%7;
b>>=1;
}
return res;
}
void getnext()
{
int j=0,k=-1;
next[0]=-1;
while(j<n)
{
if(k==-1||s[j]==s[k])
{
next[++j]=++k;
}
else
{
k=next[k];
}
}
}
int main()
{
for(int i=1;i<=600;i++)
{
f[i] = f[i-1] + Pow(i,i);
f[i]%=7;
}
for(int i=0;i<=600;i++)
{
sprintf(&s[i],"%d",f[i]);
}
s[601]=' ';
cout<<s<<endl;
getnext();
for(int i=1;i<=600;i++) //由题意可知，长度为1的字符串不算
{
len=i-next[i]; //len代表最小循环节
if(i%len==0 && i/len>1) //周期大于1才是循环串
{
cout<<"ans = "<<len<<endl;
}
}
printf("
");
}
#include<iostream>
#include<algorithm>
#include<string>
#include<map>
#include<cmath>
#include<string.h>
#include<stdlib.h>
#include<cstdio>
#define ll long long
using namespace std;
ll x[1005];
long mod(long a,long n,long b){ //a^b mod c
long t;
if(n==0) return 1%b;
if(n==1) return a%b;
t=mod(a,n/2,b);
t=t*t%b;
if((n&1)==1) t=t*a%b;
return t;}
int main(){
string s[7]={"Saturday","Sunday","Monday","Tuesday","Wednesday","Thursday","Friday"};
x[0]=0;
for(int i=1;i<=1000;++i)
x[i]=(x[i-1]%7+mod(i,i,7))%7;
int next[1001];
next[0] = 0;
int len=1000;
for(int i = 1, q = 0; i < len; i++){ //x[]里放的是要找规律的数组
while(q > 0 && x[i] != x[q])
q = next[q-1];
if (x[i] == x[q])
q++;
next[i] = q;
if (q != 0 && (i + 1) % (i + 1 - q) == 0){
printf("%d
", i+1-q); //输出的就是最大循环长度
break;
}
}
return 0;
}