프로그래머스 / 삼총사

https://school.programmers.co.kr/learn/courses/30/lessons/131705

파이썬

억지스럽게... 

from itertools import combinations
solution = lambda number: sum(1 for each in combinations(number, 3) if sum(each) == 0)

정상적으로...

from itertools import combinations


def solution(number):
    return sum(1 for each in combinations(number, 3) if sum(each) == 0)

 

코틀린

class Solution {
    fun solution(number: IntArray): Int {
        var answer: Int = 0
        for (i1 in number.indices)
            for (i2 in i1 + 1 until number.size)
                for (i3 in i2 + 1 until number.size)
                    if (number[i1] + number[i2] + number[i3] == 0) {
                        answer++
                    }
        return answer
    }
}

class Solution {
    fun solution(number: IntArray) = number.indices.sumOf { i1 ->
        (i1 + 1 until number.size).sumOf { i2 ->
            (i2 + 1 until number.size).count { i3 ->
                number[i1] + number[i2] + number[i3] == 0
            }
        }
    }
}