C program to evaluate the polynomial P(x) = anxn + an-1xn-1 + … + a0

You are given a polynomial of degree n. The polynomial is of the form P(x) = anxn + an-1xn-1 + … + a0, where the ai‘s are the coefficients.  Given an integer x, write a program that will evaluate P(x).



You are provided with a function named power( ) that takes two positive integers x & y and returns xy. If y is 0, the function returns 1.

The prototype of this function is

int power(int x, int y);

You do not have to write the program for power ( ) function. This function is automatically added at the end of the code segment that you write.

INPUT:
Line 1 contains the integers n and x separated by whitespace.

Line 2 contains the coefficients an, an-1…, a0 separated by whitespace.

OUTPUT:
A single integer which is P(x).

Implementation:

#include<stdio.h> /* function to calculate power x^y */ int power(int x, int y){ int pow=1; while (y!=0){ pow*=x; y--; } return pow; } int poly(int *a,int n,int x) { int p=0; int i; for(i=n;i>=0;i--) { p = p + a[i] * power(x,i); } return p; } int main() { int n,x; int i,a[10]; scanf("%d %d",&n,&x); //a=(int*)malloc(sizeof(int)*n+1); for(i=n;i>=0;i--) scanf("%d",&a[i]); printf("%d",poly(a,n,x)); return 0; }