大数运算

来源：互联网发布：数据结构与算法英文编辑：程序博客网时间：2024/06/05 16:21
#include<cstdio>#include<cstring>#include<iostream>#include<algorithm>#include<string>using namespace std;//两个大数相加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));   //注意细节if(s1[i]-'0'>=10){s1[i]=char((s1[i]-'0')%10+'0');if(i) s1[i-1]++;else s1='1'+s1;}}return s1;}//大数乘以整形数string Multiply(string s,int x)  //大数乘以整形数{    reverse(s.begin(),s.end());    int cmp=0;    for(int i=0;i<s.size();i++)    {        cmp=(s[i]-'0')*x+cmp;        s[i]=(cmp%10+'0');        cmp/=10;    }    while(cmp)    {        s+=(cmp%10+'0');        cmp/=10;    }    reverse(s.begin(),s.end());    return s;}//大数除以整形数string Except(string s,int x)  //大数除以整形数{    int cmp=0,ok=0;    string ans="";    for(int i=0;i<s.size();i++)    {        cmp=(cmp*10+s[i]-'0');        if(cmp>=x)        {            ok=1;            ans+=(cmp/x+'0');            cmp%=x;        }        else{            if(ok==1)                ans+='0';  //注意这里啊。才找出错误        }    }    return ans;}//两个大数相乘//思想就是模拟才乘法运算，一个大数乘以另一个大数的每一位然后相加就是结果了string Mult(string s,int x)  //大数乘以整形数{    reverse(s.begin(),s.end());    int cmp=0;    for(int i=0;i<s.size();i++)    {        cmp=(s[i]-'0')*x+cmp;        s[i]=(cmp%10+'0');        cmp/=10;    }    while(cmp)    {        s+=(cmp%10+'0');        cmp/=10;    }    reverse(s.begin(),s.end());    return s;}string Multfa(string x,string y)  //大数乘法{    string ans;    for(int i=y.size()-1,j=0;i>=0;i--,j++)    {        string tmp=Mult(x,y[i]-'0');        for(int k=0;k<j;k++)            tmp+='0';        ans=sum(ans,tmp);    }    return ans;}//浮点数的n次方string Multiply(string s,long x)  //大数乘以整形数{    reverse(s.begin(),s.end());    long cmp=0;    for(int i=0; i<s.size(); i++)    {        cmp=(s[i]-'0')*x+cmp;        s[i]=(cmp%10+'0');        cmp/=10;    }    while(cmp)    {        s+=(cmp%10+'0');        cmp/=10;    }    reverse(s.begin(),s.end());    return s;}string Remove_later(string s)   //删除一个字符串的后倒0{    int ok=1;    for(int i=s.size()-1; i>=0; i--)    {        if(s[i]=='0'){            s.erase(i);        }        else if(s[i]=='.')        {            s.erase(i);            ok=0;        }        else            ok=0;        if(ok==0)            break;    }    return s;}string factorial(string s,int n)   //浮点数的n次方{    if(n==0)        return "1";    string cmp="",count="";    long x=0,point=0;    for(int i=0; i<s.size(); i++)        if(s[i]!='.')        {            cmp+=s[i];            x=x*10+(s[i]-'0');        }        else            point=s.size()-1-i;    for(int i=1; i<n; i++)    {        cmp=Multiply(cmp,x);    }    int ans_point=cmp.size()-n*point;    if(ans_point<0)    {        count+='.';        for(int i=ans_point; i!=0; i++)            count+='0';    }    string::iterator it=cmp.begin();    if(ans_point>=0&&ans_point<cmp.size())        cmp.insert(it+ans_point,'.');    count+=(Remove_later(cmp));    return count;}//字符串去除后导0函数，前导0可以先反转取后导int main(){}
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