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BigNum.cpp
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BigNum.cpp
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// Problems.cpp : Defines the entry point for the console application.
/*
big number mully
*/
#include "stdafx.h"
#include "iostream"
#include "vector"
#include "string"
#include "map"
using namespace std;
string mul(string s1, string s2)
{
//handle sign bit
int sign=1;
if(s1.empty()||s2.empty())return "";
if(s1[0]=='+'||s1[0]=='-')
{
if(s1[0]=='-')sign=sign*(-1);
s1.erase(s1.begin());
}
if(s2[0]=='+'||s2[0]=='-')
{
if(s2[0]=='-')sign=sign*(-1);
s2.erase(s2.begin());
}
//handle float number with '.'
int point=0;
std::size_t s1p=s1.find(".");
if(s1p!=std::string::npos)
{
point+=s1.size()-1-s1p;
s1.erase(s1.begin()+s1p);
}
std::size_t s2p=s2.find(".");
if(s2p!=std::string::npos)
{
point+=s2.size()-1-s2p;
s2.erase(s2.begin()+s2p);
}
//multiply two big int number,
//number might starts or ends with '0', that's ok
int m=s1.size();
int n=s2.size();
vector<int> result(m+n, 0);
reverse(s1.begin(), s1.end());
reverse(s2.begin(), s2.end());
int carry=0;
for(int i=0;i<m;i++)
{
carry=0;
for(int j=0;j<n;j++)
{
int tmpM=(s1[i]-'0')*(s2[j]-'0');
int tmpR=(tmpM+carry+result[i+j])%10;
carry=(tmpM+carry+result[i+j])/10;
result[i+j]=tmpR;
}
if(carry)result[i+n]=carry;
}
if(carry)result[m+n-1]=carry;
reverse(result.begin(), result.end());
string tmp;
for(int i=0;i<result.size();i++)
{
tmp.push_back(result[i]+'0');
}
//handle '.'
if(point)
{
//insert the '.' into the string
tmp.insert(tmp.end()-point, '.');
//trim the '0' before '0.'
while(tmp[0]=='0')tmp.erase(tmp.begin());
if(tmp[0]=='.')tmp.insert(tmp.begin(), '0');
}
else
{
while(tmp[0]=='0')tmp.erase(tmp.begin());
}
//insert sign bit
if(sign<0)tmp.insert(tmp.begin(), '-');
return tmp;
}
int strcompare(string s1, string s2)
{
//s1 < s2 return -1
//s2 > s2 return 1
//s1 == s2 return 0
string s1I="", s1F="";
std::size_t s1p=s1.find(".");
if(s1p==string::npos)
{
s1I=s1;
s1F="";
}
else
{
s1I=s1.substr(0, s1p);
s1F=s1.substr(s1p+1, s1.size()-(s1p+1));
}
string s2I="", s2F="";
std::size_t s2p=s2.find(".");
if(s2p==string::npos)
{
s2I=s2;
s2F="";
}
else
{
s2I=s2.substr(0, s2p);
s2F=s2.substr(s2p+1, s2.size()-(s2p+1));
}
if(s1I.length()>s2I.length())return 1;
else if(s1I.length()==s2I.length())
{
int cmp=s1I.compare(s2I);
if(cmp!=0)return cmp;
else return s1F.compare(s2F);
}
else return -1;
}
string absadd(string s1, string s2)
{
int p1=0, p2=0, p=0;
std::size_t s1p=s1.find(".");
if(s1p!=string::npos)
{
p1=s1.size()-s1p-1;
s1.erase(s1.begin()+s1p);
}
std::size_t s2p=s2.find(".");
if(s2p!=string::npos)
{
p2=s2.size()-s2p-1;
s2.erase(s2.begin()+s2p);
}
string tail(abs(p1-p2), '0');
if(p1<p2)s1+=tail;
else if(p1>p2)s2+=tail;
p=max(p1, p2);
reverse(s1.begin(), s1.end());
reverse(s2.begin(), s2.end());
string result="";
int carry=0, i=0;
while(i<s1.size()&&i<s2.size())
{
int tmp=s1[i]-'0'+s2[i]-'0'+carry;
result.push_back(tmp%10+'0');
carry=tmp/10;
i++;
}
while(i<s1.size())
{
int tmp=s1[i]-'0'+carry;
result.push_back(tmp%10+'0');
carry=tmp/10;
i++;
}
while(i<s2.size())
{
int tmp=s2[i]-'0'+carry;
result.push_back(tmp%10+'0');
carry=tmp/10;
i++;
}
if(carry)result.push_back('1');
if(p)result.insert(result.begin()+p, '.');
reverse(result.begin(), result.end());
return result;
}
string abssub(string s1, string s2)
{
int p1=0, p2=0, p=0;
std::size_t s1p=s1.find(".");
if(s1p!=string::npos)
{
p1=s1.size()-s1p-1;
s1.erase(s1.begin()+s1p);
}
std::size_t s2p=s2.find(".");
if(s2p!=string::npos)
{
p2=s2.size()-s2p-1;
s2.erase(s2.begin()+s2p);
}
string tail(abs(p1-p2), '0');
if(p1<p2)s1+=tail;
else if(p1>p2)s2+=tail;
p=max(p1, p2);
reverse(s1.begin(), s1.end());
reverse(s2.begin(), s2.end());
string result="";
int carry=0, i=0;
while(i<s2.size())
{
int tmp=s1[i]-s2[i]+carry;
if(tmp>=0)
{
carry=0;
result.push_back(tmp+'0');
}
else
{
carry=-1;
result.push_back(tmp+10+'0');
}
i++;
}
while(i<s1.size())
{
int tmp=s1[i]-'0'+carry;
if(tmp>=0)
{
carry=0;
result.push_back(tmp+'0');
}
else
{
carry=-1;
result.push_back(tmp+10+'0');
}
i++;
}
if(p)result.insert(result.begin()+p, '.');
reverse(result.begin(), result.end());
while(!result.empty()&&result[0]=='0')result.erase(result.begin());
if(!result.empty()&&result[0]=='.')result.insert(result.begin(), '0');
return result;
}
string add(string s1, string s2)
{
int sign1=1;
if(s1[0]=='-')sign1=-1;
int sign2=1;
if(s2[0]=='-')sign2=-1;
int sign=1;
string result="";
if(sign1==-1&&sign2==-1)
{
s1.erase(s1.begin());
s2.erase(s2.begin());
sign=-1;
result=absadd(s1, s2);
}
else if(sign1==1&&sign2==1)
{
if(s1[0]=='+')s1.erase(s1.begin());
if(s2[0]=='+')s2.erase(s2.begin());
return absadd(s1, s2);
}
else if(sign1==-1&&sign2==1)
{
s1.erase(s1.begin());
if(s2[0]=='+')s2.erase(s2.begin());
sign=strcompare(s2, s1);
if(sign>0)result=abssub(s2, s1);
else result=abssub(s1, s2);
}
else if(sign1==1&&sign2==-1)
{
if(s1[0]=='+')s1.erase(s1.begin());
s2.erase(s2.begin());
sign=strcompare(s1, s2);
if(sign<0)result=abssub(s2, s1);
else result=abssub(s1, s2);
}
if(sign<0&&result!="0")result.insert(result.begin(), '-');
return result;
}
string sub(string s1, string s2)
{
int sign1=1;
if(s1[0]=='-')sign1=-1;
int sign2=1;
if(s2[0]=='-')sign2=-1;
int sign=1;
string result="";
if(sign1==-1&&sign2==-1)
{
s1.erase(s1.begin());
s2.erase(s2.begin());
sign=strcompare(s2, s1);
if(sign>0)result=abssub(s2, s1);
else result=abssub(s1, s2);
}
else if(sign1==1&&sign2==1)
{
if(s1[0]=='+')s1.erase(s1.begin());
if(s2[0]=='+')s2.erase(s2.begin());
sign=strcompare(s1, s2);
if(sign>0)result=abssub(s1, s2);
else result=abssub(s2, s1);
}
else if(sign1==-1&&sign2==1)
{
s1.erase(s1.begin());
if(s2[0]=='+')s2.erase(s2.begin());
sign=-1;
result=absadd(s1, s2);
}
else if(sign1==1&&sign2==-1)
{
if(s1[0]=='+')s1.erase(s1.begin());
s2.erase(s2.begin());
result=absadd(s1, s2);
}
if(sign<0&&result!="0")result.insert(result.begin(), '-');
return result;
}
int _tmain(int argc, _TCHAR* argv[])
{
/*
cout<<mul("123456789", "99999999")<<endl;
cout<<mul("12345.6789", "99999999")<<endl;
cout<<mul("12345.6789", "99999.999")<<endl;
cout<<"------"<<endl;
cout<<mul("-12345.6789", "99999999")<<endl;
cout<<mul("-12345.6789", "-9.9999999")<<endl;
cout<<mul("-12345.6789", "-9.99999990000")<<endl;
cout<<"------"<<endl;
cout<<mul("-12345.6789", "0.99999999")<<endl;
cout<<mul("-12.3456789", "+0.000000099999999")<<endl;
cout<<mul("99999999999999", "+0.000000099999999")<<endl;
*/
const int n=11;
string a[n]={"1", "12", "1234", "1.0", "1.2", "1.234", "12.34", "12345678.99", "999999.99999", "123456789987654321123456789.123456789", "9988776655443322144332211.123456789987654321"};
string b[n]={"2", "13", "1235", "2.0", "2.2", "2.23", "13.1", "12345678,123", "999999.999", "9999999999999999999999999999.999999", "99999999999999999"};
for(int i=0;i<n;i++)
{
cout<<i<<"-----------------"<<endl;
cout<<"+"<<endl;
cout<<add(a[i], b[i])<<endl;
cout<<add("+"+a[i], "+"+b[i])<<endl;
cout<<add("-"+a[i], "-"+b[i])<<endl;
cout<<sub(a[i], "-"+b[i])<<endl;
cout<<sub("-"+a[i], b[i])<<endl;
cout<<"-"<<endl;
cout<<add("-"+a[i], b[i])<<endl;
cout<<add(a[i],"-"+b[i])<<endl;
cout<<sub(a[i], b[i])<<endl;
cout<<sub("-"+a[i], "-"+b[i])<<endl;
cout<<"*"<<endl;
cout<<mul(a[i], b[i])<<endl;
cout<<mul("-"+a[i], b[i])<<endl;
cout<<mul(a[i], "-"+b[i])<<endl;
cout<<mul("-"+a[i], "-"+b[i])<<endl;
}
return 0;
}