C++ 大数版的加减乘除代码实现总结

https://blog.csdn.net/nk_test/article/details/48912763

加法：

#include
#include
#include
using namespace std;
int main()
{
    int n;
    cin>>n;
    int m=0;
    int l=0;
    for(int i=1;i<=n;i++)
    {
        string s1,s2,s(10000,'0');
        cin>>s1>>s2;
        m++;
        cout<<(l++?"\n":"");
        reverse(s1.begin(),s1.end());
        reverse(s2.begin(),s2.end());
        for(int j=0;j
        s[j]=s1[j];
        int temp=0;
        for(int k=0;k
        {
           temp+=s[k]-48+s2[k]-48;
           s[k]=temp%10+'0';
           temp/=10;
        }
        s[s2.length()]=s[s2.length()]-48+temp+48;
        reverse(s.begin(),s.end());
        reverse(s1.begin(),s1.end());
        reverse(s2.begin(),s2.end());
        cout<<"Case "<":"<
        cout<" + "<" = "<'0'))<

    }
    return 0;
}

减法：

#include
#include
#include
#include
#include
using namespace std;
int strComp(string &s1,string &s2)
{
    int len1=s1.length();
    int len2=s2.length();
    if(len1>len2)
    return 0;
    else if(len1
    return 1;
    else{
        if(s1>=s2)
        return 0;
        else
        return 1;
    }
}
int main()
{
    string s1,s2;
    while(cin>>s1>>s2)
    {
        string s(10000,'0');
        bool fgEx=true;
        if(strComp(s1,s2)==1)
        {
            string temp;
            temp=s1;
            s1=s2;
            s2=temp;
            fgEx=false;
        }
        if(s1==s2)
        {
            cout<" - "<" = "<<"0"<
            continue;
        }
        reverse(s1.begin(),s1.end());
        reverse(s2.begin(),s2.end());
        for(int i=0;i
        s[i]=s1[i];
        for(int i=0;i
        {
            if(s[i]>=s2[i])
            s[i]=s[i]-'0'-(s2[i]-'0')+'0';
            else{
                s[i+1]=s[i+1]-'0'-1+'0';
                s[i]=s[i]-'0'+10-(s2[i]-'0')+'0';
            }
        }
        if(fgEx==false)
        {
            reverse(s2.begin(),s2.end());
            cout<" - ";
            reverse(s1.begin(),s1.end());
            cout<" = ";
            reverse(s.begin(),s.end());
            cout<<"-"<'0'))<
        }
        else
        {
            reverse(s1.begin(),s1.end());
            cout<" - ";
            reverse(s2.begin(),s2.end());
            cout<" = ";
            reverse(s.begin(),s.end());
            cout<'0'))<
        }
    }
    return 0;

}

乘法：

#include
#include
#include
#include
#include
using namespace std;
int main()
{
    string s1,s2;
    while(cin>>s1>>s2)
    {
        string s(1000,'0');
        reverse(s1.begin(),s1.end());
        reverse(s2.begin(),s2.end());
        for(int i=0;i
        for(int j=0;j
        {
            int temp=(s1[i]-'0')*(s2[j]-'0');
            s[i+j+1]=s[i+j+1]-'0'+(s[i+j]-'0'+temp)/10+'0';
            s[i+j]=(s[i+j]-'0'+temp)%10+'0';
        }
        reverse(s.begin(),s.end());
        if(s.find_first_not_of('0')==string::npos)
        cout<<"0"<
        else
        cout<'0'))<
    }
    return 0;
}

除法：

#include
#include
#include
#include
#include
using namespace std;
int strComp(string &s1,string &s2)
{
    int len1=s1.length();
    int len2=s2.length();
    if(len1>len2)
    return 0;
    else if(len1
    return 1;
    else{
        if(s1>=s2)
        return 0;
        else
        return 1;
    }
}
string Sub(string s1,string s2)
{
        if(strComp(s1,s2)==1)
        return "-1";
        reverse(s1.begin(),s1.end());
        reverse(s2.begin(),s2.end());
        string s(1000,'0');
        for(int i=0;i
        s[i]=s1[i];
        for(int i=0;i
        {
            if(s[i]>=s2[i])
            s[i]=s[i]-'0'-(s2[i]-'0')+'0';
            else{
                s[i+1]=s[i+1]-'0'-1+'0';
                s[i]=s[i]-'0'+10-(s2[i]-'0')+'0';
            }
        }
        reverse(s.begin(),s.end());
        if(s.find_first_not_of('0')==string::npos)
        return "0";
        else
        return s.substr(s.find_first_not_of('0'));
}
int main()
{
    string s1,s2;
    while(cin>>s1>>s2)
    {
        string s(1000,'0');
        if(strComp(s1,s2)==1)
        {
          cout<<"0"<
          continue;
        }
        int len1=s1.length();
        int len2=s2.length();
        int dis=len1-len2;
        for(int i=0;i
        s2+='0';
        string ans(1000,'0');
        while(dis>=0)
        {
              int sum=0;
              string temp;
              while((temp=Sub(s1,s2))!="-1")
              {
                  sum++;
                  s1=temp;
              }
              ans[ans.length()-dis-1]=sum+'0';
              dis--;
              s2=s2.substr(0,len2+dis);
        }
        if(ans.find_first_not_of('0')==string::npos)
        cout<<"0"<
        else{
        string res=ans.substr(ans.find_first_not_of('0'));
        cout<
        }
    }
    return 0;
}