<Codesignal> shapeArea

Easy

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
  shapeArea(n) = 5;
• For n = 3, the output should be
  shapeArea(n) = 13.

Input/Output

• [execution time limit] 0.5 seconds (c)

• [input] integer n

  Guaranteed constraints:
  1 ≤ n < 10^4.

• [output] integer

  • The area of the n-interesting polygon.

[C] Syntax Tips

// Prints help message to the console
// Returns a string
char * helloWorld(char * name) {
    char * answer = malloc(strlen(name) + 8);
    printf("This prints to the console when you Run Tests");
    strcpy(answer, "Hello, ");
    strcat(answer, name);
    return answer;
}

---

Solution

int shapeArea(int n)
{
	int size=1;

	for(int i=1;i<n;i++)
		size+=i*4;

	return size;
}