11249. Recursion – 2

The integers a, b, c are given. For a given integer n, compute the value of the function:

Input. Four integers a, b, c (|a|, |b|, |c| ≤ 1000), n (0 ≤ n ≤ 1000).

Output. Print the value of f(n).

Sample input	Sample output
4 2 -3 10	84

RECURSION

recursion

Algorithm analysis

To solve the problem, the given recursive function should be implemented.

Algorithm realization

The function f implements the recursive function given in the problem statement.

long long f(long long n)

{

if (n == 0) return a;

return f(n - 1) + b * n + c;

}

The main part of the program. Read the input data.

scanf("%lld %lld %lld %lld", &a, &b, &c, &n);

Compute and print the answer.

res = f(n);

printf("%lld\n", res);

Python realization

The function f implements the recursive function given in the problem statement.

def f(n):

if n == 0: return a

return f(n - 1) + b * n + c

The main part of the program. Read the input data.

a, b, c, n = map(int,input().split())

Compute and print the answer.

res = f(n)

print(res)