1 /* 优点:
  2     1 支持负整数的运算
  3     2 良好的输出形式 没有前导零
  4     3 支持cin直接输入 支持cout直接输出
  5     4 支持整数的直接赋值  big_int x=100;
  6   缺点: 
  7     1 封装不好 基本都是友元函数操作
  8     2 速度慢  乘法没有使用FFT 除法采用二分法
  9               使用STL string储存数据也造成速度不是很快
 10     3 待解决的问题  不能直接输出 cout<<a-b
 11 */
 12 
 13 #include <iostream>
 14 #include <algorithm>
 15 #include <stack>
 16 using namespace std;
 17 void change (string &s) {
 18     string tmp="";
 19     int i;
 20     for (i=0;i<s.size();i++)
 21         if (s[i]!='0')
 22             break;
 23     if (i==s.size()) s="0";
 24     else {
 25         for (;i<s.size();i++)
 26             tmp+=s[i];
 27         s=tmp;
 28     }
 29 }
 30 class big_int
 31 {
 32     private :
 33         bool flag;
 34         string s;
 35     public :
 36         big_int (){ flag=1; s="0"; }
 37         big_int (int x);
 38         bool operator ==(const big_int& x)  {
 39             string tmp=x.s;
 40             change (s);
 41             change (tmp);
 42             if (x.s=="0"&&s=="0") return true;
 43             return x.flag==flag&&s==tmp;
 44         }
 45         friend big_int operator+(const big_int& a, const big_int& b );
 46         friend big_int operator-(const big_int& a, const big_int& b );
 47         friend big_int operator*(const big_int& a, const big_int& b);
 48         friend big_int operator/(const big_int& a, const big_int& b);
 49         friend big_int operator%(const big_int& a, const big_int& b);
 50         friend ostream& operator<<(ostream& out,big_int& x) {
 51             if (!x.flag&&x.s!="0") cout<<"-";
 52             change (x.s);
 53             cout<<x.s;
 54             return out;
 55         }
 56         friend istream& operator>>(istream& in,big_int& x) {
 57             string  tmp;
 58             cin>>tmp;
 59             if (tmp[0]=='-') {
 60                 x.flag=0;
 61                 x.s=tmp.substr(1,tmp.size()-1);
 62             }
 63             else {
 64                 x.flag=1;
 65                 x.s=tmp;
 66             }
 67             return in;
 68         }
 69 };
 70 big_int:: big_int (int x)  {
 71             if (x<0) flag=0;
 72             else     flag=1;
 73             x=abs(x);
 74  
 75             s="";  string tmp="0";
 76             if (x==0) s+=tmp;
 77             while (x!=0) {
 78                 tmp[0]='0'+x%10;
 79                 s+=tmp;
 80                 x/=10;
 81             }
 82             reverse(s.begin(),s.end());
 83 }
 84 string  add(string s1,string s2) {
 85     reverse(s1.begin(),s1.end());
 86     reverse(s2.begin(),s2.end());
 87     int len =max (s1.size(),s2.size());
 88     int k=0; int t1,t2;
 89     string ans="";  string tmp="0";
 90     for (int i=0;i<len;i++) {
 91         t1=t2=0;
 92         if (i<s1.size())  t1=s1[i]-'0';
 93         if (i<s2.size())  t2=s2[i]-'0';
 94         int t=t1+t2+k;
 95         tmp[0]='0'+t%10;  k=t/10;
 96         ans+=tmp;
 97     }
 98     if (k!=0) {
 99         tmp[0]='0'+k;
100         ans+=tmp;
101     }
102     reverse(ans.begin(),ans.end());
103     return ans;
104 }
105 string sub (string s1,string s2) {
106     reverse(s1.begin(),s1.end());
107     reverse(s2.begin(),s2.end());
108     int len =s1.size();
109     int t1,t2;
110     string ans="";  string tmp="0";
111     for (int i=0;i<len;i++) {
112         t1=s1[i]-'0'; t2=0;
113         if (i<s2.size())  t2=s2[i]-'0';
114         if (t1<t2) {
115             for (int j=i+1;j<len;j++)
116                 if (s1[j]-'0'==0) s1[j]='9';
117                 else {
118                     s1[j]--;
119                     break;
120                 }
121             t1+=10;
122         }
123         tmp[0]=t1-t2+'0';
124         ans+=tmp;
125     }
126     reverse(ans.begin(),ans.end());
127     change(ans);
128     return ans;
129 }
130 bool m_cmp (string s1, string s2) {
131     change (s1);
132     change (s2);
133     if (s1.size()==s2.size()) {
134         for (int i=0;i<s1.size();i++)
135             if (s1[i]!=s2[i])
136                 return s1[i]>s2[i];
137     }
138     return s1.size()>s2.size();
139 }
140 string s_mul (string s,int x,int k) {
141     string ans=""; string tmp="0";
142     for (int i=1;i<=k;i++) ans+=tmp;
143     k=0;
144     for (int i=0;i<s.size();i++) {
145         int t=s[i]-'0';
146         int p=t*x+k;
147         tmp[0]='0'+p%10; ans+=tmp;
148         k=p/10;
149     }
150     if (k)  {
151         tmp[0]='0'+k;
152         ans+=tmp;
153     }
154     reverse(ans.begin(),ans.end());
155     change(ans);
156     return ans;
157 }
158 string mul (string s1,string s2) {
159     reverse(s1.begin(),s1.end());
160     reverse(s2.begin(),s2.end());
161     string ans="0";
162     for (int i=0;i<s2.size();i++) {
163         int x=s2[i]-'0';
164         string tmp=s_mul (s1,x,i);
165         ans=add(ans,tmp);
166         //cout<<ans<<endl;
167     }
168     return ans;
169 }
170 big_int operator+(const big_int& a, const big_int& b ) {
171      big_int c;
172      int t=a.flag^b.flag;
173      if (t==0) {
174          c.s=add (a.s,b.s);
175          c.flag=a.flag;
176      }
177      else {
178         if (m_cmp(a.s,b.s))  {
179             c.flag=a.flag;
180             c.s=sub (a.s,b.s);
181         }
182         else {
183             c.flag=b.flag;
184             c.s=sub (b.s,a.s);
185         }
186      }
187      return c;
188 }
189 big_int operator-(const big_int& a, const big_int& b ) {
190     big_int c=b;
191     c.flag=!b.flag;
192     return a+c;
193 }
194 big_int operator*(const big_int& a, const big_int& b) {
195     big_int c;
196     int t=a.flag^b.flag;
197     if (t)  c.flag=0;
198     if (m_cmp(a.s,b.s)) c.s=mul (a.s,b.s);
199     else            c.s=mul (b.s,a.s);
200     return c;
201 }
202 big_int operator/(const big_int& a, const big_int& b) {
203     if (b.s=="0")  {
204         cout<<"error"<<endl;
205         exit(-1);
206     }
207     big_int c;
208     big_int _a=a, _b=b;
209     _a.flag=_b.flag=1;
210     if (m_cmp(_b.s,_a.s)) return c;
211  
212     stack <big_int> q;
213     big_int k=1;
214     while (1) {
215         big_int x=k*_b; q.push(k);
216         if (m_cmp(x.s,_a.s))
217             break;
218         k=k*2;
219     }
220     big_int tmp=_a;
221     while (tmp.s!="0"&&!q.empty()) {
222         k=q.top(); q.pop();
223         big_int x=k*_b;
224         if ( !m_cmp(x.s,tmp.s)) {
225             tmp=tmp-x;
226             c=c+k;
227         }
228     }
229     if (a.flag^b.flag)  c.flag=0;
230     return c;
231 }
232 big_int operator%(const big_int& a, const big_int& b) {
233       big_int c=a/b;
234       c=c*b;
235       c=a-c;
236       return c;
237 }
238 int main ()
239 {
240     big_int a,b;
241     big_int c=-100;  
242     cout<<c<<endl;
243     while (cin>>a>>b) {
244         c=a+12;
245         cout<<c<<" ";
246         c=a-b;
247         cout<<c<<" ";
248         c=a*b;
249         cout<<c<<" ";
250         c=a/b;
251         cout<<c<<" ";
252         c=a%b;
253         cout<<c<<endl;
254     }
255     return 0;
256 }