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Daily Challenge #225 - Square'n'Sum

#challenge

Implement a function squareSum so that it squares any number(s) passed into it and then adds the squares together.

For example, for [1, 2, 2]: it should return 9 because 1^2 + 2^2 + 2^2 = 9.

Tests
[1, 2, 3, 4]
[0, 3, 5, 7]
[2, 2, 20]

Good luck!

This challenge comes from jhoffner on CodeWars. Thank you to CodeWars, who has licensed redistribution of this challenge under the 2-Clause BSD License!

Want to propose a challenge idea for a future post? Email yo+challenge@dev.to with your suggestions!

Top comments (13)

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vidit1999 profile image
Vidit Sarkar •

I am in love with Python.

square_sum = lambda lst: sum(map(int.__mul__ , *[lst]*2)) print(square_sum([1, 2, 2])) # output -> 9 print(square_sum([1, 2, 3, 4])) # output -> 30 print(square_sum([0, 3, 5, 7])) # output -> 83 print(square_sum([2, 2, 20])) # output -> 408 print(square_sum([])) # output -> 0
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youssefrabeiii profile image
Youssef Rabei •

Javascript:

const squareSum = numbers => numbers.map(num => num ** 2).reduce((a, b) => a + b, 0)
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mellen profile image
Matt Ellen-Tsivintzeli •

Trying to find a more... unconventional javascript answer :D

function squareSum(numbers) { if(numbers.length > 0) { let n = numbers.pop(); return square(n) + squareSum(numbers); } return 0; } let squares = [0, 1]; function square(n) { let absn = Math.abs(n); if(typeof(squares[n]) !== 'undefined') { return squares[n]; } let sqr = square(absn-1) + (absn-1) + absn; squares[n] = sqr; return sqr; }
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qm3ster profile image
Mihail Malo • • Edited

Sum of squares is the default example of the Rayon crate:

use rayon::prelude::*; fn sum_of_squares(input: &[i32]) -> i32 { input.par_iter() // <-- just change that! .map(|&i| i * i) .sum() }

(this runs in parallel)

Apparently people here are really into onelinerization.

let sum_of_squares = |nums| nums.iter().map(|&i| i * i).sum();

No parallelism, but at least it's shorter than Python.

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louy2 profile image
Yufan Lou • • Edited 
squareSum = let square x = x * x in getSum . foldMap (Sum . square)

Btw, you gave "tests" but the tests don't have the supposed results. I know I can hand calculate but still they are not complete test cases.

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swizzard profile image
sam • • Edited

Point free baby!

import Data.Monoid (Sum(..)) squareSum :: (Num c, Foldable t) => t c -> c squareSum = getSum . foldMap (Sum . (^2))

(Obviously this is probably too polymorphic, you could just limit it to [Int] -> Int)

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aminnairi profile image
Amin •

Elm

I really wish flip is part of the core library...

flip : (a -> b -> c) -> (b -> a -> c) flip f a b = f b a squareSum : List Int -> Int squareSum integers = List.foldl (flip (^) 2 >> (+)) 0 integers
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kesprit profile image
kesprit •

My swift solution :

func squareSum(_ array: [Int]) -> Int { Int(array.reduce(into: 0.0) { $0 += pow(Double($1), 2) }) } squareSum([1, 2, 2]) // 9 squareSum([1, 2, 3, 4]) // 30 squareSum([0, 3, 5, 7]) // 83 squareSum([2, 2, 20]) // 408 squareSum([]) // 0
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pavi2410 profile image
Pavitra Golchha •

Python

squareSum = lambda arr: sum([n ** 2 for n in arr])
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savagepixie profile image
SavagePixie •

Elixir

def square_sum(n), do: n |> Enum.map(&(&1 * &1)) |> Enum.sum
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pavi2410 profile image
Pavitra Golchha •

Kotlin

val squareSum = { arr: List<Int> -> arr.map { it * it }.sum() }
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