BS-code.cpp

#include<iostream>
#include<bits/stdc++.h>

using namespace std;

// Program to subtract two binary numbers
void Subtract(int n, int a[], int b[]) {

   // 1's Complement of the subtrahend
   for (int i = 0; i < n; i++) {

      //Replace 1 by 0
      if (b[i] == 1) {
         b[i] = 0;
      }//Replace 0 by 1
      else {
         b[i] = 1;
      }
   }

   //Add 1 at end to get 2's Complement of the subtrahend
   for (int i = n - 1; i >= 0; i--) {
      if (b[i] == 0) {
         b[i] = 1;
         break;
      } else {
         b[i] = 0;
      }
   }

   // Represents carry
   int t = 0;
   for (int i = n - 1; i >= 0; i--) {

      // Add a, b and carry
      a[i] = a[i] + b[i] + t;

      // If a[i] is 2
      if (a[i] == 2) {
         a[i] = 0;
         t = 1;
      }// If a[i] is 3
      else if (a[i] == 3) {
         a[i] = 1;
         t = 1;
      } else
         t = 0;
   }

   cout << endl;

   // If carry is generated
   // discard the carry
   if (t == 1) {

      // print the result
      for (int i = 0; i < n; i++) {

         // Print the result
         cout << a[i];
      }
   }

      // if carry is not generated
   else {

      // Calculate 2's Complement
      // of the obtained result
      for (int i = 0; i < n; i++) {
         if (a[i] == 1)
            a[i] = 0;
         else
            a[i] = 1;
      }
      for (int i = n - 1; i >= 0; i--) {
         if (a[i] == 0) {
            a[i] = 1;
            break;
         } else
            a[i] = 0;
      }

      // Add -ve sign to represent
      cout << "-";

      // -ve result
      // Print the resultant array
      for (int i = 0; i < n; i++) {
         cout << a[i];
      }
   }
}


int main() // Main function
{
   int n;
   n = 5;
   int a[] = {1, 0, 1, 0, 1},
      b[] = {1, 0, 1, 1, 1};

   Subtract(n, a, b);
   return 0;
}