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6 done in Kotlin #180

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6 done in Kotlin
bartonstanley Oct 29, 2019
53d982d
Merge branch 'master' of https://github.com/bartonstanley/Project-Euler
bartonstanley Oct 29, 2019
71b6158
Update README.md
bartonstanley Oct 29, 2019
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31 changes: 31 additions & 0 deletions Kotlin/6.Sum_square_difference/bartonstaley.kt
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/*
Project Euler Question 6. Sum square difference

Problem Statement:

The sum of the squares of the first ten natural numbers is,

1^2 + 2^2 + ... + 10^2 = 385

The square of the sum of the first ten natural numbers is,

(1 + 2 + ... + 10)^2 = 552 = 3025

Hence the difference between the sum of the squares of the first ten
natural numbers and the square of the sum is 3025 − 385 = 2640.

Find the difference between the sum of the squares of the first one hundred
natural numbers and the square of the sum.
*/

fun Int.square() = this * this

fun sum(n: Int) = (n * (n + 1)) / 2

fun sumOfSquares(n: Int) = n * (n + 1) * (2 * n + 1) / 6

fun sumSquareDifference(n: Int) = sum(n).square() - sumOfSquares(n)

fun main(args: Array<String>) {
println("Sum square difference of 100: " + sumSquareDifference(100))
}
2 changes: 1 addition & 1 deletion README.md
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Expand Up @@ -34,7 +34,7 @@ Happy Contributing! 😃
| 03 | [Largest prime factor](https://projecteuler.net/problem=3) | :white_check_mark: | :white_check_mark: | :white_check_mark: | :white_check_mark: | | :white_check_mark: | :white_check_mark: | | :white_check_mark: | | | |
| 04 | [Largest palindrome product](https://projecteuler.net/problem=4) | :white_check_mark: | | | :white_check_mark: | | | :white_check_mark: | | | | | |
| 05 | [Smallest multiple](https://projecteuler.net/problem=5) | :white_check_mark: | | | :white_check_mark: | | | | | :white_check_mark: | | | |
| 06 | [Sum square difference](https://projecteuler.net/problem=6) | :white_check_mark: | :white_check_mark: | | :white_check_mark: | | :white_check_mark: | :white_check_mark: | | | | | |
| 06 | [Sum square difference](https://projecteuler.net/problem=6) | :white_check_mark: | :white_check_mark: | | :white_check_mark: | :white_check_mark: | :white_check_mark: | :white_check_mark: | | | | | |
| 07 | [10001st prime](https://projecteuler.net/problem=7) | :white_check_mark: | | | :white_check_mark: | | :white_check_mark: | :white_check_mark: | | | | | |
| 08 | [Largest product in a series](https://projecteuler.net/problem=8) | | | | :white_check_mark: | | | | | | | | |
| 09 | [Special Pythagorean triplet](https://projecteuler.net/problem=9) | :white_check_mark: | | | :white_check_mark: | | | | | | | | |
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