Below we will define an n-interesting polygon. Your task is to find the area of a polygon for a given n.
A 1-interesting polygon is just a square with a side of length 1. An n-interesting polygon is obtained by taking the n - 1-interesting polygon and appending 1-interesting polygons to its rim, side by side. You can see the 1-, 2-, 3- and 4-interesting polygons in the picture below.
Example
- For
n = 2, the output should be
solution(n) = 5; - For
n = 3, the output should be
solution(n) = 13.
Input/Output
-
[execution time limit] 0.5 seconds (cpp)
-
[input] integer n
Guaranteed constraints:
1 ≤ n < 10^4^. -
[output] integer
The area of the
n-interesting polygon.
int solution(int n) {
if(n==1){
return 1;
}
return solution(n-1) + 4 * (n-1);
}