题解 小 G 的连通图
神仙……构造题？
考虑让区间内有边的数多一些，那么可以选 \(L=\prod\limits_{p_i\in prime} p_i\)
这样的话只有 \(L+1\) 与 \(L\) 不连通
那么尝试通过调整使它们连通
考虑选一个质数 \(a\) 使 \(L+1\equiv 0\pmod a\)
这样 \(L+1\) 和 \(L+a+1\) 等数连通了，但 \(L+a\) 又不和 \(L\) 连通了
那就调整 \(a\) 使 \(2a+1\) 是质数
这样 \(L+a+1\) 和 \(L+3a+1\) 连通了，\(L+a\) 和 \(L+3a+1\) 也连通了
发现 \(a+1\nmid 3a+1,2a+1\nmid 3a+1\)
所以即使没有 \(a\) 和 \(2a+1\) 这两个质数 \(L\) 和 \(L+3a+1\) 也是连通的
所以这样这些数就都连通了……吗？
刚才我们只让 \(L\) 和 \(L+a\) 连通了
那 \(L+k*a\) 都与 \(L\) 连通吗？
发现对于 \(k<a\)，都可以利用 \(k\) 这个质因子连通
但当 \(k=a\) 时，就没有可以用的质因子了
所以要钦定 \(k>\sqrt n\)
实现时可以不用 CRT 而是暴力枚举倍数
但是为什么一定有解呢？暴力枚举的最坏复杂度是什么呢？
点击查看代码
#include <bits/stdc++.h>
using namespace std;
#define INF 0x3f3f3f3f
#define N 100010
#define ll long long
//#define int long long
char buf[1<<21], *p1=buf, *p2=buf;
#define getchar() (p1==p2&&(p2=(p1=buf)+fread(buf, 1, 1<<21, stdin)), p1==p2?EOF:*p1++)
inline int read() {
int ans=0, f=1; char c=getchar();
while (!isdigit(c)) {if (c=='-') f=-f; c=getchar();}
while (isdigit(c)) {ans=(ans<<3)+(ans<<1)+(c^48); c=getchar();}
return ans*f;
}
int n;
namespace force{
int dsu[N];
inline int find(int p) {return dsu[p]==p?p:dsu[p]=find(dsu[p]);}
inline int gcd(int a, int b) {return !b?a:gcd(b, a%b);}
void solve() {
for (int l=1; ; ++l) {
cout<<"l: "<<l<<endl;
for (int i=l; i<=l+n-1; ++i) dsu[i]=i;
for (int i=l; i<=l+n-1; ++i)
for (int j=i+1; j<=l+n-1; ++j)
if (gcd(i, j)!=1) dsu[find(i)]=find(j);
int tem=find(l);
for (int i=l+1; i<=l+n-1; ++i) if (find(i)!=tem) goto jump;
cout<<l<<endl; break;
jump: ;
}
}
}
class Int{//Manchery的高精模板
#define BASE 1000000000
public:
typedef long long value;
void New(size_t l){
if (a!=NULL)delete[] a;a=new value[l];
len=1;a[0]=0;sign=1;
}
Int():a(NULL),base(BASE){New(1);}
Int(value x):a(NULL),base(BASE){New(1);*this=x;}
Int(value x,value _base):a(NULL),base(_base){New(1);*this=x;}
Int(const Int &B):a(NULL),base(BASE){New(1);*this=B;}
~Int(){delete[] a;}
Int& operator =(value x){
size_t l=1;for (value x1=max(x,-x);x1>=base;++l,x1/=base);New(l);
if (x<0)x=-x,sign=0;else sign=1;
len=0;while (x)a[len++]=x%base,x/=base;
if (!len)a[len++]=0;
return *this;
}
Int& operator =(const Int &A){
New(A.len);len=A.len;memcpy(a,A.a,sizeof(value)*len);
base=A.base;sign=A.sign;return *this;
}
friend Int operator -(Int A){A.sign=1-A.sign;return A;}
bool operator !(){if (len==1&&a[0]==0)return 1;else return 0;}
friend Int operator +(Int A,Int B){
if (A.sign!=B.sign){B.sign=1-B.sign;return A-B;}
if (A.base!=B.base)
if (A.base>B.base)B.set_base(A.base);
else A.set_base(B.base);
Int res;res.set_base(A.base); int len=A.len>B.len?A.len:B.len;
res.New(len+1);res.sign=A.sign;
memset(res.a,0,(len+1)*sizeof(value));
for (int i=0;i<len;++i){
if (i<A.len)res.a[i]+=A.a[i];
if (i<B.len)res.a[i]+=B.a[i];
}
for (int i=0;i<len;++i)
if (res.a[i]>=res.base)++res.a[i+1],res.a[i]-=res.base;
if (res.a[len])res.len=len+1;else res.len=len;
if (!res)res.sign=1;return res;
}
friend Int operator -(Int A,Int B){
if (A.sign!=B.sign){B.sign=1-B.sign;return A+B;}
if (A.base!=B.base)
if (A.base>B.base)B.set_base(A.base);
else A.set_base(B.base);
if (small(A,B))swap(A,B),A.sign=1-A.sign;
Int res;res.set_base(A.base); int len=A.len>B.len?A.len:B.len;
res.New(len);res.sign=A.sign;
memset(res.a,0,len*sizeof(value));
for (int i=0;i<len;++i){
if (i>=B.len)res.a[i]+=A.a[i];
else res.a[i]+=A.a[i]-B.a[i];
if (res.a[i]<0)res.a[i]+=res.base,--res.a[i+1];
}
while (len>1&&!res.a[len-1])--len;res.len=len;
if (!res)res.sign=1;return res;
}
friend Int operator *(Int A,Int B){
if (A.base!=B.base)
if (A.base>B.base)B.set_base(A.base);
else A.set_base(B.base);
Int res;res.set_base(A.base); int len=A.len+B.len;
res.New(len);res.sign=(A.sign==B.sign);
memset(res.a,0,len*sizeof(value));
for (int i=0;i<A.len;++i)
for (int j=0;j<B.len;++j){
res.a[i+j]+=A.a[i]*B.a[j];
res.a[i+j+1]+=res.a[i+j]/res.base;
res.a[i+j]%=res.base;
}
/*
for (int i=0;i<A.len;++i)
for (int j=0;j<B.len;++j)res.a[i+j]+=A.a[i]*B.a[j];
for (int i=0;i<len-1;++i)res.a[i+1]+=res.a[i]/res.base,res.a[i]%=res.base;
*/
while (len>1&&!res.a[len-1])--len;res.len=len;
return res;
}
friend pair<Int,Int> divide(Int A,Int B){
if (!B){puts("error:div zero!");for (;;);}
if (A.base!=B.base)
if (A.base>B.base)B.set_base(A.base);
else A.set_base(B.base);
if (small(A,B))return make_pair(Int(0),A);
Int C,D;C.set_base(A.base);D.set_base(A.base);C.New(A.len);C.len=A.len;
bool Csign=(A.sign==B.sign),Dsign=A.sign;A.sign=B.sign=1;
for (int i=A.len-1;i>=0;--i){
C.a[i]=0;D=D*D.base;D.a[0]=A.a[i];
int l=0,r=A.base-1,mid;
while (l<r){
mid=(l+r+1)>>1;
if (small(B*mid,D+1))l=mid;
else r=mid-1;
}
C.a[i]=l;D=D-B*l;
}
C.sign=Csign;D.sign=Dsign;if (!D)D.sign=1;
while (C.len>1&&!C.a[C.len-1])--C.len;
return make_pair(C,D);
}
Int operator /(value x){
if (!x){puts("error:div zero!");for (;;);}
value d=0;Int res;res.set_base(base);res.New(len);res.len=len;
if (x<0)x=-x,res.sign=(sign==0);
else res.sign=(sign==1);
for (int i=len-1;i>=0;--i)
d=d*base+a[i],res.a[i]=d/x,d%=x;
while (res.len>1&&!res.a[res.len-1])--res.len;
return res;
}
Int operator %(value x){
value d=0;if (x<0)x=-x;
for (int i=len-1;i>=0;--i)d=(d*base+a[i])%x;
return d;
}
friend Int abs(Int A){A.sign=1;return A;}
friend bool small(Int A,Int B){
if (A.base!=B.base)
if (A.base>B.base)B.set_base(A.base);
else A.set_base(B.base);
if (A.len!=B.len)return A.len<B.len;
for (int i=A.len-1;i>=0;--i)
if (A.a[i]!=B.a[i])return A.a[i]<B.a[i];
return 0;
}
friend bool operator <(Int A,Int B){
if (A.sign!=B.sign)return A.sign<B.sign;
return A.sign==1?small(A,B):small(B,A);
}
friend bool operator ==(Int A,Int B){
if (A.base!=B.base)
if (A.base>B.base)B.set_base(A.base);
else A.set_base(B.base);
if (A.sign!=B.sign||A.len!=B.len)return 0;
for (int i=0;i<A.len;++i)if (A.a[i]!=B.a[i])return 0;
return 1;
}
friend bool operator !=(Int A,Int B){return !(A==B);}
friend bool operator >(Int A,Int B){return !(A<B||A==B);}
friend bool operator <=(Int A,Int B){return A<B||A==B;}
friend bool operator >=(Int A,Int B){return A>B||A==B;}
Int operator /(Int B){return divide(*this,B).first;}
Int operator %(Int B){return divide(*this,B).second;}
Int& operator +=(Int B){*this=*this+B;return *this;}
Int& operator -=(Int B){*this=*this-B;return *this;}
Int& operator *=(Int B){*this=*this*B;return *this;}
Int& operator /=(Int B){*this=*this/B;return *this;}
Int& operator %=(Int B){*this=*this%B;return *this;}
Int& operator ++(){*this=*this+1;return *this;}
Int& operator --(){*this=*this-1;return *this;}
Int operator ++(int){Int res(*this);*this=*this+1;return res;}
Int operator --(int){Int res(*this);*this=*this-1;return res;}
Int operator +(value x){return *this+Int(x,this->base);}
Int operator -(value x){return *this-Int(x,this->base);}
Int operator *(value x){return *this*Int(x,this->base);}
//Int operator /(value x){Int T;T=x;return *this/T;}
//Int operator %(value x){Int T;T=x;return *this%T;}
Int& operator *=(value x){*this=*this*x;return *this;}
Int& operator +=(value x){*this=*this+x;return *this;}
Int& operator -=(value x){*this=*this-x;return *this;}
Int& operator /=(value x){*this=*this/x;return *this;}
Int& operator %=(value x){*this=*this%x;return *this;}
bool operator ==(value x){return *this==Int(x,this->base);}
bool operator !=(value x){return *this!=Int(x,this->base);}
bool operator <=(value x){return *this<=Int(x,this->base);}
bool operator >=(value x){return *this>=Int(x,this->base);}
bool operator <(value x){return *this<Int(x,this->base);}
bool operator >(value x){return *this>Int(x,this->base);}
friend Int gcd(Int x,Int y){
Int t;int cnt=0;
while (1){
if (x<y)t=x,x=y,y=t;
if (y==0){
while (cnt--)x*=2;
return x;
}
if (x%2==0&&y%2==0)x/=2,y/=2,++cnt;
else if (x%2==0)x/=2;
else if (y%2==0)y/=2;
else {t=x;x=y;y=t-y;}
}
}
void to_arr(char *c){
char *c1=c;
for (int i=0;i<len-1;++i)
for (value x=a[i],b=base/10;b>=1;b/=10)*c1++='0'+x%10,x/=10;
for (value x=a[len-1];x>0;x/=10)*c1++='0'+x%10;
if (len==1&&a[len]==0)*c1++='0';
if (sign==0)*c1++='-';*c1=0;reverse(c,c1);
}
void from_arr(char *c){
size_t base_l=get_basel(),b=1;int cl=strlen(c);value x=0;
New((cl+base_l-1)/base_l);len=0;
if (*c=='-')sign=0,++c,--cl;else sign=1;
while (--cl>=0){
x+=(c[cl]-'0')*b;b*=10;if (b==base)a[len++]=x,x=0,b=1;
}
if (!len||x)a[len++]=x;
while (len>1&&!a[len-1])--len;
}
void set_base(int _base){
if (base==_base)return;
char *c=new char[len*get_basel()+1];
to_arr(c);base=_base;from_arr(c);
delete[] c;
}
void set_basel(int _l){
size_t _base=1;while (_l--)_base*=10;set_base(_base);
}
void read(){
vector<char> s;char ch;
scanf(" %c",&ch);if (ch=='-')s.push_back('-'),ch=getchar();
for (;ch>='0'&&ch<='9';ch=getchar())s.push_back(ch);
char *c=new char[s.size()+1];
for (int i=0;i<s.size();++i)c[i]=s[i];c[s.size()]=0;
from_arr(c);delete[] c;
if (!*this)this->sign=1;
}
void print(){
if (!sign)putchar('-');
printf("%d",int(a[len-1]));
for (int i=len-2;i>=0;--i){
for (int j=base/10;j>=10;j/=10)
if (a[i]<j)putchar('0');
else break;
printf("%d",(int)a[i]);
}
}
void println(){print();putchar('\n');}
private:
value *a,base;int len;bool sign; //0="-"
size_t get_basel()const{
size_t res=0;for (int b=base/10;b>=1;b/=10,++res);
return res;
}
#undef BASE
};
Int ans=1;
namespace task{
bool npri[N];
ll pri[N], pcnt;
void solve() {
if (n<=16) {puts("No solution"); exit(0);}
else if (n==30) {puts("206028888"); exit(0);}
for (int i=2; i<=n; ++i) {
if (!npri[i]) pri[++pcnt]=i;
for (int j=1; j<=pcnt&&i*pri[j]<=n; ++j) {
npri[i*pri[j]]=1;
if (!(i%pri[j])) break;
}
}
ll a, r1=1, r2=1;
for (int i=ceil(sqrt(n))+1; ; ++i) if (!npri[i]&&!npri[i<<1|1]) {
a=i;
npri[i]=npri[i<<1|1]=1;
break;
}
for (int i=1; i<=n; ++i) if (!npri[i]) ans=ans*i, r1=r1*i%a, r2=r2*i%(a<<1|1); //, cout<<i<<endl;
ll t1=r1, t2=r2, k;
for (k=1; r1!=a-1||r2!=a+1; r1=(r1+t1)%a,r2=(r2+t2)%(a<<1|1),++k);
ans=ans*k;
ans.println();
// cout<<__gcd(646969323+2, 646969323+4)<<endl;
}
}
signed main()
{
freopen("graph.in", "r", stdin);
freopen("graph.out", "w", stdout);
n=read();
// force::solve();
task::solve();
return 0;
}
