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  1. #include <cstdio>
  2. #include <string>
  3. #include <algorithm>
  4. #include <iostream>
  5.  
  6. using namespace std;
  7.  
  8. struct Bigint {
  9.     // representations and structures
  10.     string a; // to store the digits
  11.     int sign; // sign = -1 for negative numbers, sign = 1 otherwise
  12.  
  13.     // constructors
  14.     Bigint() {} // default constructor
  15.     Bigint( string b ) { (*this) = b; } // constructor for string
  16.  
  17.     // some helpful methods
  18.     int size() { // returns number of digits
  19.         return a.size();
  20.     }
  21.  
  22.     Bigint inverseSign() { // changes the sign
  23.         sign *= -1;
  24.         return (*this);
  25.     }
  26.  
  27.     Bigint normalize( int newSign ) { // removes leading 0, fixes sign
  28.         for( int i = a.size() - 1; i > 0 && a[i] == '0'; i-- )
  29.             a.erase(a.begin() + i);
  30.         sign = ( a.size() == 1 && a[0] == '0' ) ? 1 : newSign;
  31.         return (*this);
  32.  
  33.     }
  34.     // assignment operator
  35.     void operator = ( string b ) { // assigns a string to Bigint
  36.         a = b[0] == '-' ? b.substr(1) : b;
  37.         reverse( a.begin(), a.end() );
  38.         this->normalize( b[0] == '-' ? -1 : 1 );
  39.     }
  40.  
  41.     // conditional operators
  42.     bool operator < ( const Bigint &b ) const { // less than operator
  43.         if( sign != b.sign ) return sign < b.sign;
  44.         if( a.size() != b.a.size() )
  45.             return sign == 1 ? a.size() < b.a.size() : a.size() > b.a.size();
  46.         for( int i = a.size() - 1; i >= 0; i-- ) if( a[i] != b.a[i] )
  47.             return sign == 1 ? a[i] < b.a[i] : a[i] > b.a[i];
  48.         return false;
  49.     }
  50.     bool operator == ( const Bigint &b ) const { // operator for equality
  51.         return a == b.a && sign == b.sign;
  52.     }
  53.  
  54.     // mathematical operators
  55.     Bigint operator + ( Bigint b ) { // addition operator overloading
  56.         if( sign != b.sign ) return (*this) - b.inverseSign();
  57.         Bigint c;
  58.         for(int i = 0, carry = 0; i<a.size() || i<b.size() || carry; i++ ) {
  59.             carry+=(i<a.size() ? a[i]-48 : 0)+(i<b.a.size() ? b.a[i]-48 : 0);
  60.             c.a += (carry % 10 + 48);
  61.             carry /= 10;
  62.         }
  63.         return c.normalize(sign);
  64.     }
  65.  
  66.     Bigint operator - ( Bigint b ) { // subtraction operator overloading
  67.         if( sign != b.sign ) return (*this) + b.inverseSign();
  68.         int s = sign; sign = b.sign = 1;
  69.         if( (*this) < b ) return ((b - (*this)).inverseSign()).normalize(-s);
  70.         Bigint c;
  71.         for( int i = 0, borrow = 0; i < a.size(); i++ ) {
  72.             borrow = a[i] - borrow - (i < b.size() ? b.a[i] : 48);
  73.             c.a += borrow >= 0 ? borrow + 48 : borrow + 58;
  74.             borrow = borrow >= 0 ? 0 : 1;
  75.         }
  76.         return c.normalize(s);
  77.     }
  78.  
  79.     Bigint operator * ( Bigint b ) { // multiplication operator overloading
  80.         Bigint c("0");
  81.         for( int i = 0, k = a[i] - 48; i < a.size(); i++, k = a[i] - 48 ) {
  82.             while(k--) c = c + b; // ith digit is k, so, we add k times
  83.             b.a.insert(b.a.begin(), '0'); // multiplied by 10
  84.         }
  85.         return c.normalize(sign * b.sign);
  86.  
  87.     }
  88.  
  89.     Bigint operator / ( Bigint b ) { // division operator overloading
  90.         if( b.size() == 1 && b.a[0] == '0' ) b.a[0] /= ( b.a[0] - 48 );
  91.         Bigint c("0"), d;
  92.         for( int j = 0; j < a.size(); j++ ) d.a += "0";
  93.         int dSign = sign * b.sign; b.sign = 1;
  94.         for( int i = a.size() - 1; i >= 0; i-- ) {
  95.             c.a.insert( c.a.begin(), '0');
  96.             c = c + a.substr( i, 1 );
  97.             while( !( c < b ) ) c = c - b, d.a[i]++;
  98.         }
  99.         return d.normalize(dSign);
  100.     }
  101.  
  102.     Bigint operator % ( Bigint b ) { // modulo operator overloading
  103.         if( b.size() == 1 && b.a[0] == '0' ) b.a[0] /= ( b.a[0] - 48 );
  104.         Bigint c("0");
  105.         b.sign = 1;
  106.         for( int i = a.size() - 1; i >= 0; i-- ) {
  107.             c.a.insert( c.a.begin(), '0');
  108.             c = c + a.substr( i, 1 );
  109.             while( !( c < b ) ) c = c - b;
  110.  
  111.         }
  112.         return c.normalize(sign);
  113.     }
  114.  
  115.     // output method
  116.     void print() {
  117.         if( sign == -1 ) putchar('-');
  118.         for( int i = a.size() - 1; i >= 0; i-- ) putchar(a[i]);
  119.     }
  120. };
  121.  
  122.  
  123. int main() {
  124.  
  125.     Bigint a, b, c; // declared some Bigint variables
  126.     /////////////////////////
  127.  
  128.     // taking Bigint input //
  129.  
  130.     /////////////////////////
  131.     string input; // string to take input
  132.     cin >> input; // take the Big integer as string
  133.  
  134.     a = input; // assign the string to Bigint a
  135.  
  136.     cin >> input; // take the Big integer as string
  137.     b = input; // assign the string to Bigint b
  138.  
  139.  
  140.     //////////////////////////////////
  141.  
  142.     // Using mathematical operators //
  143.  
  144.     //////////////////////////////////
  145.  
  146.  
  147.  
  148.     c = a + b; // adding a and b
  149.     c.print(); // printing the Bigint
  150.     puts(""); // newline
  151.  
  152.  
  153.     c = a - b; // subtracting b from a
  154.     c.print(); // printing the Bigint
  155.     puts(""); // newline
  156.  
  157.  
  158.     c = a * b; // multiplying a and b
  159.     c.print(); // printing the Bigint
  160.     puts(""); // newline
  161.  
  162.  
  163.     c = a / b; // dividing a by b
  164.     c.print(); // printing the Bigint
  165.     puts(""); // newline
  166.  
  167.     c = a % b; // a modulo b
  168.     c.print(); // printing the Bigint
  169.     puts(""); // newline
  170.  
  171.     /////////////////////////////////
  172.  
  173.     // Using conditional operators //
  174.  
  175.     /////////////////////////////////
  176.  
  177.     if( a == b ) puts("equal"); // checking equality
  178.  
  179.     else puts("not equal");
  180.     if( a < b ) puts("a is smaller than b"); // checking less than operator
  181.  
  182.  
  183.  
  184.     return 0;
  185.  
  186. }
  187.  
Success #stdin #stdout 0s 3456KB
comments (?)
stdin
copy 
999999999999999999999999999
55555555555555555555555555
stdout
copy 
1055555555555555555555555554
944444444444444444444444444
55555555555555555555555554944444444444444444444444445
18
9
not equal
https://ideone.com/7sgc4J
Big Integer
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
public

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