package leetcode_study

import io.kotest.matchers.collections.shouldContainExactlyInAnyOrder

import org.junit.jupiter.api.Test

class `3sum` {

fun threeSum(nums: IntArray): List<List<Int>> {

return usingTwoPointer(nums)

}

/**

private fun usingIterative(nums: IntArray): List<List<Int>> {

val result = mutableSetOf<List<Int>>()

for (first in nums.indices) {

for (second in first + 1 until nums.size) {

for (third in second + 1 until nums.size) {

if (nums[first] + nums[second] + nums[third] == 0) {

result.add(listOf(nums[first], nums[second], nums[third]).sorted())

}

}

}

}

return result.toList()

}

/**

private fun usingTwoPointer(nums: IntArray): List<List<Int>> {

val sortedNumbers = nums.sorted()

val result = mutableSetOf<List<Int>>()

for (index in nums.indices) {

var left = index + 1

var right = nums.size - 1

while (left < right) {

val sum = sortedNumbers[index] + sortedNumbers[left] + sortedNumbers[right]

if (sum == 0) {

result.add(listOf(sortedNumbers[index], sortedNumbers[left], sortedNumbers[right]))

left++

right--

} else if (sum < 0) {

left++

} else {

right--

}

}

}

return result.toList()

}

@Test

fun `입력받은 정수 배열의 세 개의 원소의 합이 0이 되는 리스트를 반환한다`() {

threeSum(intArrayOf(-1,0,1,2,-1,-4)) shouldContainExactlyInAnyOrder listOf(

listOf(-1,-1,2),

listOf(-1,0,1)

)

threeSum(intArrayOf(0,0,0)) shouldContainExactlyInAnyOrder listOf(

listOf(0,0,0)

)

}

}