#include <stdio.h>
#include <stdlib.h>

typedef struct {
  int coeff;
  int expo;
} Poly;

int readPoly(Poly *p);
int addPoly(Poly *p1, Poly *p2, Poly *p3, int t1, int t2);
void displayPoly(Poly *p, int terms);

int main() {
  Poly *p1, *p2, *p3;
  int t1, t2, t3;

  p1 = (Poly *)malloc(10 * sizeof(Poly));
  p2 = (Poly *)malloc(10 * sizeof(Poly));
  p3 = (Poly *)malloc(10 * sizeof(Poly));

  printf("First Polynomial: \n");
  t1 = readPoly(p1);
  displayPoly(p1, t1);

  printf("\nSecond Polynomial: \n");
  t2 = readPoly(p2);
  displayPoly(p2, t2);

  printf("\nResultant Polynomial: \n");
  t3 = addPoly(p1, p2, p3, t1, t2);
  displayPoly(p3, t3);
}

int readPoly(Poly *p) {
  int terms;

  printf("Enter the number of terms: ");
  scanf("%d", &terms);

  for (int i=0; i<terms; i++) {
    printf("Enter the coefficient: ");
    scanf("%d", &p[i].coeff);
    printf("Enter the exponent: ");
    scanf("%d", &p[i].expo);
  }

  return terms;
}

int addPoly(Poly *p1, Poly *p2, Poly *p3, int t1, int t2) {
  int i, j, k;
  i = j = k = 0;

  while (i < t1 && j < t2) {
    if (p1[i].expo == p2[j].expo) {
      p3[k].expo = p1[i].expo;
      p3[k].coeff = p1[i].coeff + p2[j].coeff;
      i++, j++, k++;
    }

    if (p1[i].expo > p2[j].expo) {
      p3[k].expo = p1[i].expo;
      p3[k].coeff = p1[i].coeff;
      i++, k++;
    }

    if (p2[j].expo > p1[i].expo) {
      p3[k].expo = p2[j].expo;
      p3[k].coeff = p2[j].coeff;
      j++, k++;
    }
  }

  while (i < t1) {
    p3[k].expo = p1[i].expo;
    p3[k].coeff = p1[i].coeff;

    i++, k++;
  }

  while (j < t2) {
    p3[k].expo = p2[j].expo;
    p3[k].coeff = p2[j].coeff;

    j++, k++;
  }

  return k;
}


void displayPoly(Poly *p, int terms) {
  int t;
  for (t=0; t<terms-1; t++) {
    printf("(%d)x^%d + ", p[t].coeff, p[t].expo);
  }
  printf("(%d)x^%d", p[t].coeff, p[t].expo);
}