大数问题

// 实数加减法#include<cstdio>#include<iostream>#include<algorithm>using namespace std;string rever(string a){        string b;        for(int i = 0;i<a.size();i++)        b = a[i] + b;        return b;}int main(){   // freopen("input.txt","r",stdin);    int n,m;    string a,b;    while(cin>>a>>b)    {        int i = 0,j = 0;        while(a[i++]!='.'&&i<=a.size());        if(i <= a.size())        {            n = a.size()-i;            a.erase(a.begin()+i-1);        }        else n = 0;      //  cout<<a<<" "<<b<<endl;        while(b[j++]!='.'&&j<=b.size());        if(j <= b.size())        {            m = b.size()-j;            b.erase(b.begin()+j-1);        }        else m = 0;        int mmax = max(n,m);        while(n<m){        a = a + '0';        n++;        }        while(m<n){        b = b + '0';        m ++;        }        int g;        a = rever(a);        b = rever(b);        char c[100008];        int cn = 0;        string s="";       // puts("in");        for(i=0,g=0;g||i<max(a.size(),b.size());i++)        {           int x = g;           if(i<a.size())x+=a[i]-'0';           if(i<b.size())x+=b[i]-'0';           c[cn++] = x%10 +'0' ;           s = c[cn-1] + s;           g = x/10;        }        s.insert(s.end()-mmax,'.');        for( i=s.size()-1;i>=0;i--)        if(s[i]>'0'&&s[i]<='9')        break;        else{        char cs = s[i];        s.erase(s.begin()+i);        if(cs == '.')break;        }        cout<<s<<endl;    }}

大数加法：

 #include<string>#include<cstdio>#include<algorithm>#include<iostream>#include<cstring>using namespace std;const int maxn = 1000;struct  bign{    int len,s[maxn];    bign()    {        memset(s,0,sizeof(s));        len = 1;    }    bign operator = (const char *num)    {        len = strlen(num);        for(int i=0;i<len;i++)s[i] = num[len-i-1] - '0';        return *this;    }    bign operator = (int num)    {       // cout<<"in"<<endl;        char s[maxn];        sprintf(s,"%d",num);        *this = s;        return *this;    }    bign(int num){*this = num;}    bign(const char *num){ *this = num ;}    string str()const    {        string res = "";        for(int i=0;i<len;i++)        res = (char)(s[i] + '0') + res;        if (res == "")res = "0";        return res;    }    bign operator + (const bign& b)const    {       bign c;       c.len = 0;       for(int i=0,g = 0;g|| i<max(len,b.len);i++)       {           int x = g;           if(i<len) x+= s[i];           if(i<b.len) x+=b.s[i];           c.s[c.len++] = x%10;           g = x/10;       }       return c;    }     void clean()    {        while(len > 1 && !s[len-1]) len--;    }    bign operator += (const bign& b)    {        *this = *this + b;        return *this;    }};istream& operator >>(istream &in, bign& x){    string s;    in>>s;    x = s.c_str();    return in;}ostream& operator << (ostream &out, const bign& x){   out << x.str();    return out;}bign f[1002];int main(){  for(int i=0;i<1000;i++)  f[i] = 0;  f[1] = 1;  f[0] = 1;  for(int i=2;i<=1000;i++)  f[i] = f[i-1]+f[i-2];  int m;  while(cin>>f[1]>>f[2])  {      cout<<f[1]+f[2]<<endl;  }}        

大数乘除法：

#include<stdio.h>#include<cstring>#include<iostream>const int base = 10000;const int Max = 100;using namespace std;void Mul(int a[],int fax,int b){    int i,arr = 0;    for(i = fax -1;i >= 0;i--)    {        arr +=b*a[i];        a[i] = arr%base;        arr /= base;    }}void Div(int a[],int fax,int b){    int i,div = 0;    for(int i=0;i<fax;i++)    {        div = div*base + a[i];        a[i] = div / b;        div %= b;    }}int main(){    int n,m,i;    int a[101][Max];    memset(a[1],0,Max*sizeof(int));    for( i=2,a[1][Max-1] =1;i<101;i++)    {        memcpy(a[i],a[i-1],Max*sizeof(int));        Mul(a[i],Max,4*i-2);        Div(a[i],Max,i+1);    }    while(cin>>n)    {        for( i=0;i<100&&a[n][i]==0;i++);        cout<<a[n][i++];        for(;i<Max;i++)        {            printf("%04d",a[n][i]);        }        cout<<endl;    } return 0;}