///////    File: Poly.C    ///////
#include <iostream.h>
#include "Poly.h"

#define MAX(x,y) ((x) > (y) ? (x) : (y))
#define MIN(x,y) ((x) < (y) ? (x) : (y))

Poly::Poly(int *p, int n)      // constructor
{   n = 2*n;
    pol = new int[n+1];        // dynamic allocation
    for ( int i=0 ; i < n ; i++ )
         pol[i] = *p++;
    pol[n] = -1;               // terminator
}

int Poly::length()         // private member
{  for (int i=0 ; pol[i] > -1 ; i += 2);
   return(i+1);
}

Poly Poly::operator+(Poly q)
{ int *c, *a, *b, *tmp;
  unsigned len, d;
     len = length()+q.length()-1;
     d = 1+2*(1+ MAX(deg(), q.deg()));
     len = MIN(len, d);                   // max length of answer      
     tmp = c = new(int[len]);             // temporary space for result 
     a = pol; b = q.pol;
     while (*a >= 0)                      // for each term of a            
     {   while(*b > *a)                   // terms in b of higher power    
         {   *c++ = *b++;
             *c++ = *b++;
         }
         *c++ = *a;
         if (*a == *b)                    // add terms of like power (1)  
         {   *c = *++a + *++b;
             if (*c++ == 0) c -= 2;       // terms cancel            (2) 
             b++;
         }
         else *c++ = *++a;                // no terms to combine           
         a++;
     }
     while (*b >= 0) *c++ = *b++;         // add left over terms in b      
     *c = -1;                             // terminator                    
     Poly ans(tmp, (c-tmp)/2);            // answer object
     delete tmp;                          // free temporary space
     return(ans);
}

void Poly::display()
{ int *p = pol;
     switch ( *p )
     { case -1:                          // zero poly
          cout << "0" << endl; break;
       case 0:                           // constant poly
          cout << p[1] << endl; break;
       default:
          cout << '(';                   // display terms
          while ( *p >= 0 )
          {  cout << *p << "  " << *(p+1);
             p += 2;
             if (*p != -1) cout << ", ";
          }
          cout << ")\n";
     }
}