大数模板

小鱼儿 2022-01-06 12:47 202阅读 0赞

大数加法

string temp1,temp2,temp,str;
    string sum(string s1,string s2)
    {
        if(s1.length()<s2.length())
        {
            string temp=s1;
            s1=s2;
            s2=temp;
        }
        int i,j;
        for(i=s1.length()-1,j=s2.length()-1; i>=0; i--,j--)
        {
            s1[i]=char(s1[i]+(j>=0?s2[j]-'0':0));
            if(s1[i]-'0'>=10)
            {
                s1[i]=char((s1[i]-'0')%10+'0');
                if(i)
                    s1[i-1]++;
                else
                    s1='1'+s1;
            }
        }
        return s1;
    }
    string cmp(string aa,string bb)
    {
        if(aa.size()>bb.size())
            return bb;
        if(aa.size()<bb.size())
            return aa;
        if(aa<bb)
            return aa;
        return bb;
    }

大数乘法

#include <iostream>
    #include <cstdio>
    #include <string>
    #include <cstring>
    #include <algorithm>
    #include <cmath>
    #define N 30001
    using namespace std ;
    string mul(string a1,string b1)
    {
        int lena = a1.size(), lenb =  b1.size(),x;
        int a[N],b[N],c[N];
        memset(a,0,sizeof(a));
        memset(b,0,sizeof(b));
        memset(c,0,sizeof(c));
        for ( int i = 0 ; i < lena ; i ++ )
            a [ lena - i ] = a1 [ i ] - 48 ;
        for ( int i = 0 ; i < lenb ; i ++ )
            b [ lenb - i ] = b1 [ i ] - 48 ;
        for ( int i = 0 ; i <= lena ; i ++ )
        {
            x = 0 ;  //用来存放进位
            for ( int j = 1 ; j <= lenb ; j ++ )
            {
                c [ i + j - 1 ] += a [ i ] * b [ j ] + x ;
                x = c [ i + j - 1 ] / 10 ;
                c [ i + j - 1 ] %= 10 ;
            }
            c [ i + lenb ] = x ;         //进位
        }
        int lenc = lena + lenb ;
        while ( c [ lenc ] == 0 && lenc > 1 )
            lenc -- ;
        string res;
        res.clear();
        for ( int i = lenc ; i > 0 ; i -- )
            res+=('0'+c[i]);
        return res;
    }
    int main()
    {
        string x="1",y[55];
        for(int i=0; i<5; i++)
        {
            for(int j=0; j<=9; j++)
            {
                if(i==0)
                    y[i*10+j]='0'+j;
                else
                {
                    y[i*10+j]='0'+i;
                    y[i*10+j]+='0'+j;
                }
            }
        }
        y[50]="50";
        for(int i=2; i<=50; i++)
            x=mul(x,y[i]);
        cout<<x<<endl;
        return 0;
    }

转载于:https://www.cnblogs.com/SDUTNING/p/11046148.html