shape-area.ts

export type Input = number;
export type Output = number;

/**
 * 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.
 *
 * @param n
 */
export const shapeArea = (n: Input): Output => n * n + (n - 1) * (n - 1);