Compute the Perimeter of a Polygon – HackerRank Solution

In this post, we will solve Compute the Perimeter of a Polygon HackerRank Solution. This problem (Compute the Perimeter of a Polygon) is a part of HackerRank Functional Programming series.

Task

You are given the cartesian coordinates of a set of points in a 2D plane. When traversed sequentially, these points form a Polygon, P, which is not self-intersecting in nature. Can you compute the perimeter of polygon P?

Input Format

The first line contains an integer, N, denoting the number of points.
The N subsequent lines each contain 2 space-separated integers denoting the respective x and y coordinates of a point.

Constraints

• No 2 points are coincident, and polygon P is obtained by traversing the points in a clockwise direction.
• 3 <= N <= 1000
• 0 <= x, y <= 1000

Output Format

For each test case, print the perimeter of P (correct to a scale of one decimal place).

Note: Do not add any leading/trailing spaces or units.

Sample Input

4
0 0
0 1  
1 1  
1 0

Sample Output

4

Explanation

The given polygon is a square, and each of its sides are 1 unit in length. perimeter(P) = 1 + 1 + 1 + 1 = 4, so we print 4 on a new line.

Solution – Compute the Perimeter of a Polygon – HackerRank Solution

Haskell

d [x,y,x1,y1] = sqrt $ (x1 - x)^2 + (y1 - y)^2
d _ = 0

p [] acc = acc
p points acc = p (drop 2 points) (acc + (d (take 4 points)))

perimeter points = p (points ++ (take 2 points)) 0

main :: IO ()
main = do
    _ <- getLine
    x <- getContents
    let f = map read $ words x
    print $ perimeter f

Note: This problem (Compute the Perimeter of a Polygon) is generated by HackerRank but the solution is provided by CodingBroz. This tutorial is only for Educational and Learning purpose.