H. GSS and Simple Math Problem 高精度乘法模板

链接：https://www.nowcoder.com/acm/contest/104/G
来源：牛客网

题目描述

Given n positive integers , your task is to calculate the product of these integers, The answer is less than

题解：直接python高精度

坑：c++高精度会T

紫书上的高精度乘法改不来

t = int(input())
p=1
for i in range(t):   
    s = int(input())
    p=p*s
print (p)

附：紫书上的高精度乘法：

#include<bits/stdc++.h>
#define lson (rt<<1)
#define rson (rt<<1|1)
#define mp make_pair
#define fi first
#define se second
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
const int MAXN=1111;
const int MOD=(int)1e9+7;
struct BigInt{
    const static int Base=(int)1e9;
    const static int Len=9;
    vector<int>a;
    BigInt(){a={0};}
    BigInt(const char *str,const int &l,const int &r){
        for(int i=r-Len+1;;i-=Len){
            int tmp=0;
            if(i<l){
                for(int j=l;j<i+Len;j++)tmp=tmp*10+str[j]-'0';
                a.push_back(tmp);
                break;
            }
            for(int j=i;j<i+Len;j++)tmp=tmp*10+str[j]-'0';
            a.push_back(tmp);
 
        }
        while(a.back()==0&&a.size()>1)a.pop_back();
    }
    BigInt operator *(const BigInt &b)const{
        BigInt res;
        res.a.resize(a.size()+b.a.size());
        for(int i=0;i<(int)a.size();i++){
            int up=0;
            for(int j=0;j<(int)b.a.size();j++){
                ll tmp=1ll*a[i]*b.a[j]+res.a[i+j]+up;
                res.a[i+j]=tmp%Base;
                up=tmp/Base;
            }
            if(up!=0)res.a[i+(int)b.a.size()]=up;
        }
        while(res.a.back()==0&&res.a.size()>1)res.a.pop_back();
        return res;
    }
    void display(){
        printf("%d",a.back());
        for(int i=(int)a.size()-2;i>=0;i--)printf("%09d",a[i]);
 
    }
}ans;
char str[100005];
int main()
{
    int n;
    scanf("%d",&n);
    for(int i=1;i<=n;i++){
        scanf("%s",str);
        if(i==1)ans=BigInt(str,0,strlen(str)-1);
        else {
            ans=ans*BigInt(str,0,strlen(str)-1);
        }
    }
    ans.display();
    return 0;
}
/*
20 1
12345678912345678912
*/

以及某丧心病狂的高精度

#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:1024000000,1024000000")
#define mem(a,b) memset((a),(b),sizeof(a))
#define MP make_pair
#define pb push_back
#define fi first
#define se second
#define sz(x) (int)x.size()
#define all(x) x.begin(),x.end()
using namespace std;
#define _GLIBCXX_PERMIT_BACKWARD_HASH
#include <ext/hash_map>
using namespace __gnu_cxx;
struct str_hash{size_t operator()(const string& str)const{return __stl_hash_string(str.c_str());}};
typedef long long ll;
typedef unsigned long long ull;
#define PII pair<int,int>
#define PLL pair<ll,ll>
#define PDD pair<double,double>
const int INF=0x3f3f3f3f;
const ll LLINF=0x3f3f3f3f3f3f3f3f;
const double PI=acos(-1.0);
const double eps=1e-8;
const int MAX=2e6+10;
const ll mod=1e9+7;
const int DIGIT=9;
const int DEPTH=1000000000;
const int MAXN=12000;
typedef ll bignum_t[MAXN+1];
ll read(bignum_t a,istream&is=cin)
{
    char buf[MAXN*DIGIT+1],ch;
    ll i,j;
    memset((void*)a,0,sizeof(bignum_t));
    if(!(is>>buf))return 0;
    for(a[0]=strlen(buf),i=a[0]/2-1;i>=0;i--)
    ch=buf[i],buf[i]=buf[a[0]-1-i],buf[a[0]-1-i]=ch;
    for(a[0]=(a[0]+DIGIT-1)/DIGIT,j=strlen(buf);j<a[0]*DIGIT;buf[j++]='0');
    for(i=1;i<=a[0];i++)
    for(a[i]=0,j=0;j<DIGIT;j++)
    a[i]=a[i]*10+buf[i*DIGIT-1-j]-'0';
    for(;!a[a[0]]&&a[0]>1;a[0]--);
    return 1;
}
void write(const bignum_t a,ostream&os=cout)
{
    ll i,j ;
    for(os<<a[i=a[0]],i--;i;i--)
    os<<setw(DIGIT)<<setfill('0')<<a[i];
}
ll comp(const bignum_t a,const bignum_t b)
{
    ll i ;
    if(a[0]!=b[0]) return a[0]-b[0];
    for(i=a[0];i;i--)
    if(a[i]!=b[i])
    return a[i]-b[i];
    return 0 ;
}
ll comp(const bignum_t a,const ll b)
{
    ll c[12]={1};
    for(c[1]=b;c[c[0]]>=DEPTH;c[c[0]+1]=c[c[0]]/DEPTH,c[c[0]]%=DEPTH,c[0]++);
    return comp(a,c);
}
ll comp(const bignum_t a,const ll c,const ll d,const bignum_t b)
{
    ll i,t=0,O=-DEPTH*2;
    if(b[0]-a[0]<d&&c)
    return 1 ;
    for(i=b[0];i>d;i--)
    {
        t=t*DEPTH+a[i-d]*c-b[i];
        if(t>0)return 1;
        if(t<O)return 0;
    }
    for(i=d;i;i--)
    {
        t=t*DEPTH-b[i];
        if(t>0)return 1;
        if(t<O)return 0;
    }
    return t>0 ;
}
void add(bignum_t a,const bignum_t b)
{
    ll i ;
    for(i=1;i<=b[0];i++)
    if((a[i]+=b[i])>=DEPTH)
    a[i]-=DEPTH,a[i+1]++;
    if(b[0]>=a[0])
    a[0]=b[0];
    else
    for(;a[i]>=DEPTH&&i<a[0];a[i]-=DEPTH,i++,a[i]++);
    a[0]+=(a[a[0]+1]>0);
}
void add(bignum_t a,const ll b)
{
    ll i=1;
    for(a[1]+=b;a[i]>=DEPTH&&i<a[0];a[i+1]+=a[i]/DEPTH,a[i]%=DEPTH,i++);
    for(;a[a[0]]>=DEPTH;a[a[0]+1]=a[a[0]]/DEPTH,a[a[0]]%=DEPTH,a[0]++);
}
void sub(bignum_t a,const bignum_t b)
{
    ll i;
    for(i=1;i<=b[0];i++)
    if((a[i]-=b[i])<0)
    a[i+1]--,a[i]+=DEPTH;
    for(;a[i]<0;a[i]+=DEPTH,i++,a[i]--);
    for(;!a[a[0]]&&a[0]>1;a[0]--);
}
void sub(bignum_t a,const ll b)
{
    ll i=1;
    for(a[1]-=b;a[i]<0;a[i+1]+=(a[i]-DEPTH+1)/DEPTH,a[i]-=(a[i]-DEPTH+1)/DEPTH*DEPTH,i++);
    for(;!a[a[0]]&&a[0]>1;a[0]--);
}
void sub(bignum_t a,const bignum_t b,const ll c,const ll d)
{
    ll i,O=b[0]+d;
    for(i=1+d;i<=O;i++)
    if((a[i]-=b[i-d]*c)<0)
    a[i+1]+=(a[i]-DEPTH+1)/DEPTH,a[i]-=(a[i]-DEPTH+1)/DEPTH*DEPTH ;
    for(;a[i]<0;a[i+1]+=(a[i]-DEPTH+1)/DEPTH,a[i]-=(a[i]-DEPTH+1)/DEPTH*DEPTH,i++);
    for(;!a[a[0]]&&a[0]>1;a[0]--);
}
void mul(bignum_t c,const bignum_t a,const bignum_t b)
{
    ll i,j;
    memset((void*)c,0,sizeof(bignum_t));
    for(c[0]=a[0]+b[0]-1,i=1;i<=a[0];i++)
    for(j=1;j<=b[0];j++)
    if((c[i+j-1]+=a[i]*b[j])>=DEPTH)
    c[i+j]+=c[i+j-1]/DEPTH,c[i+j-1]%=DEPTH;
    for(c[0]+=(c[c[0]+1]>0);!c[c[0]]&&c[0]>1;c[0]--);
}
void mul(bignum_t a,const ll b)
{
    ll i;
    for(a[1]*=b,i=2;i<=a[0];i++)
    {
        a[i]*=b ;
        if(a[i-1]>=DEPTH)
        a[i]+=a[i-1]/DEPTH,a[i-1]%=DEPTH;
    }
    for(;a[a[0]]>=DEPTH;a[a[0]+1]=a[a[0]]/DEPTH,a[a[0]]%=DEPTH,a[0]++);
    for(;!a[a[0]]&&a[0]>1;a[0]--);
}
void mul(bignum_t b,const bignum_t a,const ll c,const ll d)
{
    ll i;
    memset((void*)b,0,sizeof(bignum_t));
    for(b[0]=a[0]+d,i=d+1;i<=b[0];i++)
    if((b[i]+=a[i-d]*c)>=DEPTH)
    b[i+1]+=b[i]/DEPTH,b[i]%=DEPTH ;
    for(;b[b[0]+1];b[0]++,b[b[0]+1]=b[b[0]]/DEPTH,b[b[0]]%=DEPTH);
    for(;!b[b[0]]&&b[0]>1;b[0]--);
}
void div(bignum_t c,bignum_t a,const bignum_t b)
{
    ll h,l,m,i;
    memset((void*)c,0,sizeof(bignum_t));
    c[0]=(b[0]<a[0]+1)?(a[0]-b[0]+2):1 ;
    for(i=c[0];i;sub(a,b,c[i]=m,i-1),i--)
    for(h=DEPTH-1,l=0,m=(h+l+1)>>1;h>l;m=(h+l+1)>>1)
    if(comp(b,m,i-1,a))h=m-1;
    else l=m;
    for(;!c[c[0]]&&c[0]>1;c[0]--);
    c[0]=c[0]>1?c[0]:1;
}
void div(bignum_t a,const ll b,ll&c)
{
    ll i;
    for(c=0,i=a[0];i;c=c*DEPTH+a[i],a[i]=c/b,c%=b,i--);
    for(;!a[a[0]]&&a[0]>1;a[0]--);
}
void sqrt(bignum_t b,bignum_t a)
{
    ll h,l,m,i;
    memset((void*)b,0,sizeof(bignum_t));
    for(i=b[0]=(a[0]+1)>>1;i;sub(a,b,m,i-1),b[i]+=m,i--)
    for(h=DEPTH-1,l=0,b[i]=m=(h+l+1)>>1;h>l;b[i]=m=(h+l+1)>>1)
    if(comp(b,m,i-1,a))h=m-1;
    else l=m;
    for(;!b[b[0]]&&b[0]>1;b[0]--);
    for(i=1;i<=b[0];b[i++]>>=1);
}
ll length(const bignum_t a)
{
    ll t,ret;
    for(ret=(a[0]-1)*DIGIT,t=a[a[0]];t;t/=10,ret++);
    return ret>0?ret:1;
}
ll digit(const bignum_t a,const ll b)
{
    ll i,ret;
    for(ret=a[(b-1)/DIGIT+1],i=(b-1)%DIGIT;i;ret/=10,i--);
    return ret%10;
}
ll zeronum(const bignum_t a)
{
    ll ret,t;
    for(ret=0;!a[ret+1];ret++);
    for(t=a[ret+1],ret*=DIGIT;!(t%10);t/=10,ret++);
    return ret;
}
void comp(ll*a,const ll l,const ll h,const ll d)
{
    ll i,j,t;
    for(i=l;i<=h;i++)
    for(t=i,j=2;t>1;j++)
    while(!(t%j))
    a[j]+=d,t/=j;
}
void convert(ll*a,const ll h,bignum_t b)
{
    ll i,j,t=1;
    memset(b,0,sizeof(bignum_t));
    for(b[0]=b[1]=1,i=2;i<=h;i++)
    if(a[i])
    for(j=a[i];j;t*=i,j--)
    if(t*i>DEPTH)
    mul(b,t),t=1;
    mul(b,t);
}
#define SGN(x) ((x)>0?1:((x)<0?-1:0))
#define ABS(x) ((x)>0?(x):-(x))
ll read(bignum_t a,ll&sgn,istream&is=cin)
{
    char str[MAXN*DIGIT+2],ch,*buf;
    ll i,j;
    memset((void*)a,0,sizeof(bignum_t));
    if(!(is>>str))return 0;
    buf=str,sgn=1;
    if(*buf=='-')sgn=-1,buf++;
    for(a[0]=strlen(buf),i=a[0]/2-1;i>=0;i--)
    ch=buf[i],buf[i]=buf[a[0]-1-i],buf[a[0]-1-i]=ch ;
    for(a[0]=(a[0]+DIGIT-1)/DIGIT,j=strlen(buf);j<a[0]*DIGIT;buf[j++]='0');
    for(i=1;i<=a[0];i++)
    for(a[i]=0,j=0;j<DIGIT;j++)
    a[i]=a[i]*10+buf[i*DIGIT-1-j]-'0';
    for(;!a[a[0]]&&a[0]>1;a[0]--);
    if(a[0]==1&&!a[1])sgn=0;
    return 1;
}
struct bigint
{
    bignum_t num;
    ll sgn;
    bigint(ll v){*this = v;}
    inline bigint()
    {
        memset(num,0,sizeof(bignum_t));
        num[0]=1;
        sgn=0;
    }
    inline ll operator!()
    {
        return num[0]==1&&!num[1];
    }
    inline bigint&operator=(const bigint&a)
    {
        memcpy(num,a.num,sizeof(bignum_t));
        sgn=a.sgn;
        return*this;
    }
    inline bigint&operator=(const ll a)
    {
        memset(num,0,sizeof(bignum_t));
        num[0]=1;
        sgn=SGN (a);
        add(num,sgn*a);
        return*this;
    }
    inline bigint&operator+=(const bigint&a)
    {
        if(sgn==a.sgn)add(num,a.num);
        else if(sgn&&a.sgn)
        {
            ll ret=comp(num,a.num);
            if(ret>0)sub(num,a.num);
            else if(ret<0)
            {
                bignum_t t;
                memcpy(t,num,sizeof(bignum_t));
                memcpy(num,a.num,sizeof(bignum_t));
                sub (num,t);
                sgn=a.sgn;
            }
            else memset(num,0,sizeof(bignum_t)),num[0]=1,sgn=0;
        }
        else if(!sgn) memcpy(num,a.num,sizeof(bignum_t)),sgn=a.sgn;
        return*this;
    }
    inline bigint&operator+=(const ll a)
    {
        if(sgn*a>0)add(num,ABS(a));
        else if(sgn&&a)
        {
            ll  ret=comp(num,ABS(a));
            if(ret>0)sub(num,ABS(a));
            else if(ret<0)
            {
                bignum_t t;
                memcpy(t,num,sizeof(bignum_t));
                memset(num,0,sizeof(bignum_t));
                num[0]=1;
                add(num,ABS (a));
                sgn=-sgn;
                sub(num,t);
            }
            else memset(num,0,sizeof(bignum_t)),num[0]=1,sgn=0 ;
        }
        else if(!sgn) sgn=SGN(a),add(num,ABS(a));
        return*this;
    }
    inline bigint operator+(const bigint&a)
    {
        bigint ret;
        memcpy(ret.num,num,sizeof(bignum_t));
        ret.sgn=sgn;
        ret+=a;
        return ret;
    }
    inline bigint operator+(const ll a)
    {
        bigint ret;
        memcpy(ret.num,num,sizeof (bignum_t));
        ret.sgn=sgn;
        ret+=a;
        return ret;
    }
    inline bigint&operator-=(const bigint&a)
    {
        if(sgn*a.sgn<0)add(num,a.num);
        else if(sgn&&a.sgn)
        {
            ll ret=comp(num,a.num);
            if(ret>0)sub(num,a.num);
            else if(ret<0)
            {
                bignum_t t;
                memcpy(t,num,sizeof(bignum_t));
                memcpy(num,a.num,sizeof(bignum_t));
                sub(num,t);
                sgn=-sgn;
            }
            else memset(num,0,sizeof(bignum_t)),num[0]=1,sgn=0;
        }
        else if(!sgn)add(num,a.num),sgn=-a.sgn ;
        return*this ;
    }
    inline bigint&operator-=(const ll a)
    {
        if(sgn*a<0)add(num,ABS(a));
        else if(sgn&&a)
        {
            ll ret=comp(num,ABS(a));
            if(ret>0)sub(num,ABS(a));
            else if(ret<0)
            {
                bignum_t t;
                memcpy(t,num,sizeof(bignum_t));
                memset(num,0,sizeof(bignum_t));
                num[0]=1;
                add(num,ABS(a));
                sub(num,t);
                sgn=-sgn;
            }
            else memset(num,0,sizeof(bignum_t)),num[0]=1,sgn=0;
        }
        else if(!sgn)sgn=-SGN(a),add(num,ABS(a));
        return*this ;
    }
    inline bigint operator-(const bigint&a)
    {
        bigint ret;
        memcpy(ret.num,num,sizeof(bignum_t));
        ret.sgn=sgn;
        ret-=a;
        return ret;
    }
    inline bigint operator-(const ll a)
    {
        bigint ret;
        memcpy(ret.num,num,sizeof(bignum_t));
        ret.sgn=sgn;
        ret-=a;
        return ret;
    }
    inline bigint&operator*=(const bigint&a)
    {
        bignum_t t;
        mul(t,num,a.num);
        memcpy(num,t,sizeof(bignum_t));
        sgn*=a.sgn;
        return*this;
    }
    inline bigint&operator*=(const ll a)
    {
        mul(num,ABS(a));
        sgn*=SGN(a);
        return*this;
    }
    inline bigint operator*(const bigint&a)
    {
        bigint ret;
        mul(ret.num,num,a.num);
        ret.sgn=sgn*a.sgn ;
        return ret;
    }
    inline bigint operator*(const ll a)
    {
        bigint ret;
        memcpy(ret.num,num,sizeof(bignum_t));
        mul(ret.num,ABS(a));
        ret.sgn=sgn*SGN(a);
        return ret;
    }
    inline bigint&operator/=(const bigint&a)
    {
        bignum_t t;
        div(t,num,a.num);
        memcpy (num,t,sizeof(bignum_t));
        sgn=(num[0]==1&&!num[1])?0:sgn*a.sgn ;
        return*this;
    }
    inline bigint&operator/=(const ll a)
    {
        ll t;
        div(num,ABS(a),t);
        sgn=(num[0]==1&&!num [1])?0:sgn*SGN(a);
        return*this;
    }
    inline bigint operator/(const bigint&a)
    {
        bigint ret;
        bignum_t t;
        memcpy(t,num,sizeof(bignum_t));
        div(ret.num,t,a.num);
        ret.sgn=(ret.num[0]==1&&!ret.num[1])?0:sgn*a.sgn ;
        return ret;
    }
    inline bigint operator/(const ll a)
    {
        bigint ret;
        ll t;
        memcpy(ret.num,num,sizeof(bignum_t));
        div(ret.num,ABS(a),t);
        ret.sgn=(ret.num[0]==1&&!ret.num[1])?0:sgn*SGN(a);
        return ret;
    }
    inline bigint&operator%=(const bigint&a)
    {
        bignum_t t;
        div(t,num,a.num);
        if(num[0]==1&&!num[1])sgn=0;
        return*this;
    }
    inline ll operator%=(const ll a)
    {
        ll t;
        div(num,ABS(a),t);
        memset(num,0,sizeof(bignum_t));
        num[0]=1;
        add(num,t);
        return t;
    }
    inline bigint operator%(const bigint&a)
    {
        bigint ret;
        bignum_t t;
        memcpy(ret.num,num,sizeof(bignum_t));
        div(t,ret.num,a.num);
        ret.sgn=(ret.num[0]==1&&!ret.num [1])?0:sgn;
        return ret;
    }
    inline ll operator%(const ll a)
    {
        bigint ret;
        ll t;
        memcpy(ret.num,num,sizeof(bignum_t));
        div(ret.num,ABS(a),t);
        memset(ret.num,0,sizeof(bignum_t));
        ret.num[0]=1;
        add(ret.num,t);
        return t;
    }
    inline ll operator>(const bigint&a)
    {
        return sgn>0?(a.sgn>0?comp(num,a.num)>0:1):(sgn<0?(a.sgn<0?comp(num,a.num)<0:0):a.sgn<0);
    }
    inline ll operator>(const ll a)
    {
        return sgn>0?(a>0?comp(num,a)>0:1):(sgn<0?(a<0?comp(num,-a)<0:0):a<0);
    }
    inline ll operator>=(const bigint&a)
    {
        return sgn>0?(a.sgn>0?comp(num,a.num)>=0:1):(sgn<0?(a.sgn<0?comp(num,a.num)<=0:0):a.sgn<=0);
    }
    inline ll operator>=(const ll a)
    {
        return sgn>0?(a>0?comp(num,a)>=0:1):(sgn<0?(a<0?comp(num,-a)<=0:0):a<=0);
    }
    inline ll operator<(const bigint&a)
    {
        return sgn<0?(a.sgn<0?comp(num,a.num)>0:1):(sgn>0?(a.sgn>0?comp(num,a.num)<0:0):a.sgn>0);
    }
    inline ll operator<(const ll a)
    {
        return sgn<0?(a<0?comp(num,-a)>0:1):(sgn>0?(a>0?comp(num,a)<0:0):a>0);
    }
    inline ll operator<=(const bigint&a)
    {
        return sgn<0?(a.sgn<0?comp(num,a.num)>=0:1):(sgn>0?(a.sgn>0?comp(num,a.num)<=0:0):a.sgn>=0);
    }
    inline ll operator<=(const ll a)
    {
        return sgn<0?(a<0?comp(num,-a)>=0:1):(sgn>0?(a>0?comp(num,a)<=0:0):a>=0);
    }
    inline ll operator==(const bigint&a)
    {
        return(sgn==a.sgn)?!comp(num,a.num):0;
    }
    inline ll operator==(const ll a)
    {
        return(sgn*a>=0)?!comp(num,ABS(a)):0;
    }
    inline ll operator!=(const bigint&a)
    {
        return(sgn==a.sgn)?comp(num,a.num):1 ;
    }
    inline ll operator!=(const ll a)
    {
        return(sgn*a>=0)?comp(num,ABS(a)):1 ;
    }
    inline ll operator[](const ll a)
    {
        return digit(num,a);
    }
    friend inline istream&operator>>(istream&is,bigint&a)
    {
        read(a.num,a.sgn,is);
        return is;
    }
    friend inline ostream&operator<<(ostream&os,const bigint&a)
    {
        if(a.sgn<0) os<<'-';
        write(a.num,os);
        return os;
    }
    friend inline bigint sqrt(const bigint&a)
    {
        bigint ret;
        bignum_t t;
        memcpy(t,a.num,sizeof(bignum_t));
        sqrt(ret.num,t);
        ret.sgn=ret.num[0]!=1||ret.num[1];
        return ret;
    }
    friend inline bigint sqrt(const bigint&a,bigint&b)
    {
        bigint ret;
        memcpy(b.num,a.num,sizeof(bignum_t));
        sqrt(ret.num,b.num);
        ret.sgn=ret.num[0]!=1||ret.num[1];
        b.sgn=b.num[0]!=1||ret.num[1];
        return ret;
    }
    inline ll length()
    {
        return :: length(num);
    }
    inline ll zeronum()
    {
        return :: zeronum(num);
    }
};
 
int main()
{
    int n,i;
    bigint x,ans;
    while(~scanf("%d",&n))
    {
        ans=1;
        for(i=0;i<n;i++)
        {
            cin>>x;
            ans=ans*x;
        }
        cout<<ans<<"\n";
    }
    return 0;
}