홀짝트리 (with Kotlin)

https://school.programmers.co.kr/learn/courses/30/lessons/388354

프로그래머스

apply 메서드를 이용해서 graph, queue를 생성과 동시에 초기화했다.

const val MAX = 1_000_001

var answer: IntArray = intArrayOf(0, 0)

class Solution {
    fun solution(nodes: IntArray, edges: Array<IntArray>): IntArray {
        val graph = Array(MAX) { mutableListOf<Int>() }.apply {
            edges.forEach { (a, b) -> 
                get(a).add(b)
                get(b).add(a)
            }
        }
        val visited = BooleanArray(MAX) { false }
        
        for (node in nodes) {
            if (visited[node]) continue
            
            val queue = ArrayDeque<Int>().apply { addLast(node) }
            
            var (case1, case2) = 0 to 0
            
            while (queue.isNotEmpty()) {
                val currentNode = queue.removeFirst()
                visited[currentNode] = true
                
                val flag = (currentNode % 2) xor (graph[currentNode].size % 2)
                when(flag) {
                    0 -> case1++
                    1 -> case2++
                }
                
                graph[currentNode]
                    .filterNot { visited[it] }
                    .forEach { nextNode -> queue.addLast(nextNode) }
            }
            
            if (case1 == 1) answer[0]++
            if (case2 == 1) answer[1]++
        }
        
        return answer
    }
}