NPTEL Evaluating a Polynomial

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).

CONSTRAINTS: The inputs will satisfy the following properties. It is not necessary to validate the inputs.

1 <= n <= 10 1 <= x <= 10

0 <= ai <=10

Solution:

#include<stdio.h> int power(int x, int y); int main() { int n,x,i; scanf("%d%d",&n,&x); int arr[n+1]; for(i=n; i>=0; i--) { scanf("%d",&arr[i]); } int result =0; for(i=n;i>0;i--) { result += arr[i]*power(x,i); } result += arr[i]; printf("%d",result); return 0; } /* THE CODE BELOW WILL BE AUTOMATICALLY UNCOMMENTED DURING EXECUTION. PLEASE DO NOT MODIFY ANYTHING BELOW THIS LINE.*/ // int power(int x, int y) // { // int result = x; // // if(y == 0) return 1; // if(x < 0 || y < 0) return 0; // // for(int i = 1; i < y; ++i) // result *= x; // // return result; //}