C/C++ :: Define Polynomial Using Linked List

I'm try to write a program which define a polynomial using a linked list.

1) I fill every node of the list which list is as long as the value of the max power of the polynomial.
2) I print it out the resulting polynomial.
3) I want to re-scan the poly in search for the polynomials with the same index and sum them each other for having only one element with the same index, for instance, if I enter P(x) = 1 + x + x^2 + 3*x^2 + x^3, I want to obtain:
P(x) = 1 + x + (1 + 3)*x^2 + x^3.

I called this function SeekForSameIndex().

But with this example I have 4x^2 + 4x^2 + x^3, losing the firsts members of the expression, I'm behind this problem for days and I do not understand where's the mistake.

Here my code:

#include <stdio.h>
#include <stdlib.h>
struct SPoly {
int coeff;
unsigned int index;

[Code] ....