一个用来屯高精度类板子的模板.
基本都是用最朴素的万进制压位实现的高精度，乘法没有FFT，除法没有倍增.
代码如下：
typedef long long LL; #define memset(a) memset(a,0,sizeof(a)) struct unsigned_bigint{ int a[N+9],n; unsigned_bigint(int X=0){memset(a);for (n=0;X;X/=10000) a[++n]=X%10000;if (!n) n=1;} unsigned_bigint(LL X){memset(a);for (n=0;X;X/=10000) a[++n]=X%10000;if (!n) n=1;} unsigned_bigint(char *S,int N){ memset(a);n=N; for (int i=4;i<n+4;i+=4){ int t=i/4; if (i<n+1) a[t]=S[n-i+1]-'0'; if (i<n+2) a[t]=a[t]*10+S[n-i+2]-'0'; if (i<n+3) a[t]=a[t]*10+S[n-i+3]-'0'; if (i<n+4) a[t]=a[t]*10+S[n-i+4]-'0'; } for (;!a[n];--n); if (!n) n=1; } unsigned_bigint(char *S){ memset(a);n=strlen(S+1); for (int i=4;i<n+4;i+=4){ int t=i>>2; if (i<n+1) a[t]=S[n-i+1]-'0'; if (i<n+2) a[t]=a[t]*10+S[n-i+2]-'0'; if (i<n+3) a[t]=a[t]*10+S[n-i+3]-'0'; if (i<n+4) a[t]=a[t]*10+S[n-i+4]-'0'; } for (;!a[n];--n); if (!n) n=1; } unsigned_bigint(string S){ memset(a);n=S.size(); for (int i=4;i<n+4;i+=4){ int t=i>>2; if (i<=n) a[t]=S[n-i]-'0'; if (i<=n+1) a[t]=a[t]*10+S[n-i+1]-'0'; if (i<=n+2) a[t]=a[t]*10+S[n-i+2]-'0'; if (i<=n+3) a[t]=a[t]*10+S[n-i+3]-'0'; } for (;!a[n];--n); if (!n) n=1; } int &operator [] (const int &p){return a[p];} friend istream &operator >> (istream &in,unsigned_bigint &p){ string s; in>>s; p=unsigned_bigint(s); return in; } friend ostream &operator << (ostream &out,const unsigned_bigint &p){ out<<p.a[p.n]; for (int i=p.n-1;i>=1;--i){ if (p.a[i]<1000) out<<0; if (p.a[i]<100) out<<0; if (p.a[i]<10) out<<0; out<<p.a[i]; } return out; } bool operator < (const unsigned_bigint &p)const{ if (n^p.n) return n<p.n; for (int i=n;i>=0;--i) if (a[i]^p.a[i]) return a[i]<p.a[i]; return 0; } bool operator > (const unsigned_bigint &p)const{return p<*this;} bool operator <= (const unsigned_bigint &p)const{return !(*this>p);} bool operator >= (const unsigned_bigint &p)const{return !(*this<p);} bool operator == (const unsigned_bigint &p)const{return *this<=p&&*this>=p;} bool operator != (const unsigned_bigint &p)const{return *this<p||*this>p;} bool operator < (const int &p)const{return *this<unsigned_bigint(p);} bool operator < (const LL &p)const{return *this<unsigned_bigint(p);} bool operator < (const string &p)const{return *this<unsigned_bigint(p);} bool operator < (const char *p)const{return *this<unsigned_bigint(p);} bool operator > (const int &p)const{return *this>unsigned_bigint(p);} bool operator > (const LL &p)const{return *this>unsigned_bigint(p);} bool operator > (const string &p)const{return *this>unsigned_bigint(p);} bool operator > (const char *p)const{return *this>unsigned_bigint(p);} bool operator <= (const int &p)const{return *this<=unsigned_bigint(p);} bool operator <= (const LL &p)const{return *this<=unsigned_bigint(p);} bool operator <= (const string &p)const{return *this<=unsigned_bigint(p);} bool operator <= (const char *p)const{return *this<=unsigned_bigint(p);} bool operator >= (const int &p)const{return *this>=unsigned_bigint(p);} bool operator >= (const LL &p)const{return *this>=unsigned_bigint(p);} bool operator >= (const string &p)const{return *this>=unsigned_bigint(p);} bool operator >= (const char *p)const{return *this>=unsigned_bigint(p);} bool operator == (const int &p)const{return *this==unsigned_bigint(p);} bool operator == (const LL &p)const{return *this==unsigned_bigint(p);} bool operator == (const string &p)const{return *this==unsigned_bigint(p);} bool operator == (const char *p)const{return *this==unsigned_bigint(p);} bool operator != (const int &p)const{return *this!=unsigned_bigint(p);} bool operator != (const LL &p)const{return *this!=unsigned_bigint(p);} bool operator != (const string &p)const{return *this!=unsigned_bigint(p);} bool operator != (const char *p)const{return *this!=unsigned_bigint(p);} unsigned_bigint operator + (const unsigned_bigint &p)const{ unsigned_bigint res; res.n=max(n,p.n); for (int i=1;i<=res.n;++i){ res.a[i]+=a[i]+p.a[i]; if (res.a[i]>=10000) ++res.a[i+1],res.a[i]-=10000; } if (res.a[res.n+1]) ++res.n; return res; } unsigned_bigint operator + (const int &p)const{return *this+unsigned_bigint(p);} unsigned_bigint operator + (const LL &p)const{return *this+unsigned_bigint(p);} unsigned_bigint operator + (const char *s)const{return *this+unsigned_bigint(s);} unsigned_bigint operator + (const string s)const{return *this+unsigned_bigint(s);} unsigned_bigint &operator += (const unsigned_bigint &p){return *this=*this+p;} unsigned_bigint &operator += (const int &p){return *this=*this+p;} unsigned_bigint &operator += (const LL &p){return *this=*this+p;} unsigned_bigint &operator += (const char &p){return *this=*this+p;} unsigned_bigint &operator += (const string &p){return *this=*this+p;} unsigned_bigint operator - (const unsigned_bigint &p)const{ unsigned_bigint res; res.n=n; for (int i=1;i<=res.n;++i){ res.a[i]+=a[i]-p.a[i]; if (res.a[i]<0) --res.a[i+1],res.a[i]+=10000; } for (;res.n>1&&!res.a[res.n];--res.n); return res; } unsigned_bigint operator - (const int &p)const{return *this-unsigned_bigint(p);} unsigned_bigint operator - (const LL &p)const{return *this-unsigned_bigint(p);} unsigned_bigint operator - (const char *s)const{return *this-unsigned_bigint(s);} unsigned_bigint operator - (const string s)const{return *this-unsigned_bigint(s);} unsigned_bigint &operator -= (const unsigned_bigint &p){return *this=*this-p;} unsigned_bigint &operator -= (const int &p){return *this=*this-p;} unsigned_bigint &operator -= (const LL &p){return *this=*this-p;} unsigned_bigint &operator -= (const char &p){return *this=*this-p;} unsigned_bigint &operator -= (const string &p){return *this=*this-p;} unsigned_bigint operator * (const unsigned_bigint &p)const{ unsigned_bigint res; res.n=n+p.n-1; for (int i=1;i<=n;++i) for (int j=1;j<=p.n;++j){ res.a[i+j-1]+=a[i]*p.a[j]; res.a[i+j]+=res.a[i+j-1]/10000;res.a[i+j-1]%=10000; } if (res.a[res.n+1]) ++res.n; for (;!res.a[res.n]&&res.n>1;--res.n); return res; } unsigned_bigint operator * (const int &p)const{ if (p>100000) return *this*unsigned_bigint(p); unsigned_bigint res; res.n=n+8; for (int i=1;i<=res.n;++i){ res.a[i]+=a[i]*p; res.a[i+1]+=res.a[i]/10000;res.a[i]%=10000; } for (;!res.a[res.n]&&res.n>1;--res.n); return res; } unsigned_bigint operator * (const LL &p)const{return *this*unsigned_bigint(p);} unsigned_bigint operator * (const char *s)const{return *this*unsigned_bigint(s);} unsigned_bigint operator * (const string s)const{return *this*unsigned_bigint(s);} unsigned_bigint &operator *= (const unsigned_bigint &p){return *this=*this*p;} unsigned_bigint &operator *= (const int &p){return *this=*this*p;} unsigned_bigint &operator *= (const LL &p){return *this=*this*p;} unsigned_bigint &operator *= (const char &p){return *this=*this*p;} unsigned_bigint &operator *= (const string &p){return *this=*this*p;} unsigned_bigint operator / (const unsigned_bigint &p)const{ unsigned_bigint res,now=unsigned_bigint(0); for (int i=n;i>=1;--i){ now=now*10000+a[i]; for (;now>=p;now-=p) ++res.a[i]; } for (res.n=n;!res.a[res.n]&&res.n>1;--res.n); return res; } unsigned_bigint operator / (const int &p)const{ if (p>100000) return *this/unsigned_bigint(p); unsigned_bigint res; int now=0; for (int i=n;i>=1;--i){ now=now*10000+a[i]; res.a[i]=now/p;now%=p; } for (res.n=n;!res.a[res.n]&&res.n>1;--res.n); return res; } unsigned_bigint operator / (const LL &p)const{return *this/unsigned_bigint(p);} unsigned_bigint operator / (const char *s)const{return *this/unsigned_bigint(s);} unsigned_bigint operator / (const string s)const{return *this/unsigned_bigint(s);} unsigned_bigint &operator /= (const unsigned_bigint &p){return *this=*this/p;} unsigned_bigint &operator /= (const int &p){return *this=*this/p;} unsigned_bigint &operator /= (const LL &p){return *this=*this/p;} unsigned_bigint &operator /= (const char &p){return *this=*this/p;} unsigned_bigint &operator /= (const string &p){return *this=*this/p;} unsigned_bigint operator % (const unsigned_bigint &p)const{ unsigned_bigint res=unsigned_bigint(0); for (int i=n;i>=1;--i){ res=res*10000+a[i]; for (;res>=p;res-=p); } return res; } unsigned_bigint operator % (const int &p)const{ if (p>100000) return *this%unsigned_bigint(p); int res=0; for (int i=n;i>=1;--i) res=(res*10000+a[i])%p; return unsigned_bigint(res); } unsigned_bigint operator % (const LL &p)const{return *this%unsigned_bigint(p);} unsigned_bigint operator % (const char *s)const{return *this%unsigned_bigint(s);} unsigned_bigint operator % (const string s)const{return *this%unsigned_bigint(s);} unsigned_bigint &operator %= (const unsigned_bigint &p){return *this=*this%p;} unsigned_bigint &operator %= (const int &p){return *this=*this%p;} unsigned_bigint &operator %= (const LL &p){return *this=*this%p;} unsigned_bigint &operator %= (const char &p){return *this=*this%p;} unsigned_bigint &operator %= (const string &p){return *this=*this%p;} int Get_int(){ int res=0; for (int i=n;i>=1;--i) res=res*10000+a[i]; return res; } }; unsigned_bigint operator * (const int &k,const unsigned_bigint &a){return a*k;} struct bigint{ int opt; unsigned_bigint a; bigint(int X=0){opt=X<0;a=unsigned_bigint(abs(X));} bigint(LL X){opt=X<0;a=unsigned_bigint(abs(X));} bigint(char *S,int N){opt=S[1]=='-';a=unsigned_bigint(S[1]=='-'?(S+1,N-1):(S,N));} bigint(char *S){opt=S[1]=='-';a=unsigned_bigint(S[1]=='-'?S+1:S);} bigint(string S){opt=S[0]=='-';if (S[0]=='-') S.erase(0,1);a=unsigned_bigint(S);} bigint(int Opt,unsigned_bigint A){opt=Opt;a=A;} int &operator [] (const int &p){return a[p];} friend istream &operator >> (istream &in,bigint &p){string s;in>>s;p=bigint(s);return in;} friend ostream &operator << (ostream &out,const bigint &p){ if (p.opt&&(p.a.n^1||p.a.a[1]^0)) out<<'-'; out<<p.a; return out; } bool operator < (const bigint &p)const{if (opt^p.opt) return opt>p.opt;return opt?a>p.a:a<p.a;} bool operator > (const bigint &p)const{return p<*this;} bool operator <= (const bigint &p)const{return !(*this>p);} bool operator >= (const bigint &p)const{return !(*this<p);} bool operator == (const bigint &p)const{return *this<=p&&*this>=p;} bool operator != (const bigint &p)const{return *this<p||*this>p;} bool operator < (const int &p)const{return *this<bigint(p);} bool operator < (const LL &p)const{return *this<bigint(p);} bool operator < (const string &p)const{return *this<bigint(p);} bool operator < (const char *p)const{return *this<bigint(p);} bool operator > (const int &p)const{return *this>bigint(p);} bool operator > (const LL &p)const{return *this>bigint(p);} bool operator > (const string &p)const{return *this>bigint(p);} bool operator > (const char *p)const{return *this>bigint(p);} bool operator <= (const int &p)const{return *this<=bigint(p);} bool operator <= (const LL &p)const{return *this<=bigint(p);} bool operator <= (const string &p)const{return *this<=bigint(p);} bool operator <= (const char *p)const{return *this<=bigint(p);} bool operator >= (const int &p)const{return *this>=bigint(p);} bool operator >= (const LL &p)const{return *this>=bigint(p);} bool operator >= (const string &p)const{return *this>=bigint(p);} bool operator >= (const char *p)const{return *this>=bigint(p);} bool operator == (const int &p)const{return *this==bigint(p);} bool operator == (const LL &p)const{return *this==bigint(p);} bool operator == (const string &p)const{return *this==bigint(p);} bool operator == (const char *p)const{return *this==bigint(p);} bool operator != (const int &p)const{return *this!=bigint(p);} bool operator != (const LL &p)const{return *this!=bigint(p);} bool operator != (const string &p)const{return *this!=bigint(p);} bool operator != (const char *p)const{return *this!=bigint(p);} bigint operator - (){return bigint(opt^1,a);} bigint operator + (const bigint &p)const{ return opt==p.opt?bigint(opt,a+p.a):bigint(opt^a<p.a,a<p.a?p.a-a:a-p.a); } bigint operator + (const int &p)const{return *this+bigint(p);} bigint operator + (const LL &p)const{return *this+bigint(p);} bigint operator + (const char *s)const{return *this+bigint(s);} bigint operator + (const string s)const{return *this+bigint(s);} bigint &operator += (const bigint &p){return *this=*this+p;} bigint &operator += (const int &p){return *this=*this+p;} bigint &operator += (const LL &p){return *this=*this+p;} bigint &operator += (const char &p){return *this=*this+p;} bigint &operator += (const string &p){return *this=*this+p;} bigint operator - (const bigint &p)const{return *this+bigint(p.opt^1,p.a);} bigint operator - (const int &p)const{return *this-bigint(p);} bigint operator - (const LL &p)const{return *this-bigint(p);} bigint operator - (const char *s)const{return *this-bigint(s);} bigint operator - (const string s)const{return *this-bigint(s);} bigint &operator -= (const bigint &p){return *this=*this-p;} bigint &operator -= (const int &p){return *this=*this-p;} bigint &operator -= (const LL &p){return *this=*this-p;} bigint &operator -= (const char &p){return *this=*this-p;} bigint &operator -= (const string &p){return *this=*this-p;} bigint operator * (const bigint &p)const{return bigint(opt^p.opt,a*p.a);} bigint operator * (const int &p)const{return bigint(opt^p<0,a*abs(p));} bigint operator * (const LL &p)const{return *this*bigint(p);} bigint operator * (const char *s)const{return *this*bigint(s);} bigint operator * (const string s)const{return *this*bigint(s);} bigint &operator *= (const bigint &p){return *this=*this*p;} bigint &operator *= (const int &p){return *this=*this*p;} bigint &operator *= (const LL &p){return *this=*this*p;} bigint &operator *= (const char &p){return *this=*this*p;} bigint &operator *= (const string &p){return *this=*this*p;} bigint operator / (const bigint &p)const{return bigint(opt^p.opt,a/p.a);} bigint operator / (const int &p)const{return bigint(opt^p<0,a/abs(p));} bigint operator / (const LL &p)const{return *this/bigint(p);} bigint operator / (const char *s)const{return *this/bigint(s);} bigint operator / (const string s)const{return *this/bigint(s);} bigint &operator /= (const bigint &p){return *this=*this/p;} bigint &operator /= (const int &p){return *this=*this/p;} bigint &operator /= (const LL &p){return *this=*this/p;} bigint &operator /= (const char &p){return *this=*this/p;} bigint &operator /= (const string &p){return *this=*this/p;} bigint operator % (const bigint &p)const{return bigint(opt,a%p.a);} bigint operator % (const int &p)const{return bigint(opt,a%p);} bigint operator % (const LL &p)const{return *this%bigint(p);} bigint operator % (const char *s)const{return *this%bigint(s);} bigint operator % (const string s)const{return *this%bigint(s);} bigint &operator %= (const bigint &p){return *this=*this%p;} bigint &operator %= (const int &p){return *this=*this%p;} bigint &operator %= (const LL &p){return *this=*this%p;} bigint &operator %= (const char &p){return *this=*this%p;} bigint &operator %= (const string &p){return *this=*this%p;} int Get_int(){return a.Get_int()*(opt?-1:1);} }; bigint operator * (const int &k,const bigint &a){return a*k;}