자물쇠와 열쇠 (with Kotlin)

https://school.programmers.co.kr/learn/courses/30/lessons/60059

프로그래머스

2차원 배열을 deep copy하기 위해서 새로운 객체에 각 행을 clone해서 초기화한다. 

class Solution {
    fun Array<IntArray>.rotate(): Array<IntArray> {
        val n = this.size
        val result = Array(n) { IntArray(n) }
        for (i in 0 until n) {
            for (j in 0 until n) {
                result[j][n - 1 - i] = this[i][j]
            }
        }
        return result
    }

    fun Array<IntArray>.check(M: Int, N: Int): Boolean {
        for (x in M until M + N) {
            for (y in M until M + N) {
                if (this[x][y] != 1) return false
            }
        }
        return true
    }

    fun solution(key: Array<IntArray>, lock: Array<IntArray>): Boolean {
        val (M, N) = key.size to lock.size
        val size = 2 * M + N
        val matrix = Array(size) { IntArray(size) }.apply {
            for (r in M until M + N) {
                for (c in M until M + N) {
                    get(r)[c] = lock[r - M][c - M]
                }
            }    
        }

        var rotatedKey = key
        
        repeat(4) {
            rotatedKey = rotatedKey.rotate()
            for (r in 1 until M + N) {
                for (c in 1 until M + N) {
                    val cmpMatrix = Array(size) { matrix[it].clone() }

                    for (x in 0 until M) {
                        for (y in 0 until M) {
                            cmpMatrix[r + x][c + y] += rotatedKey[x][y]
                        }
                    }
                    
                    if (cmpMatrix.check(M, N)) return true
                }
            }
        }
        
        return false
    }
}