[백준] #16926: 배열 돌리기

문제링크

1. Notation

• n : 세로
• m : 가로
• r : 회전 횟수
• sub : 한 번 회전 시, 필요한 회전 수

2. Source Code

fun main() {
    val br = System.`in`.bufferedReader()
    val bw = System.out.bufferedWriter()

    val (n, m, r) = br.readLine().split(" ").map { it.toInt() }
    val arr = Array(n) { mutableListOf<Int>() }
    repeat(n) {
        arr[it] = br.readLine().split(" ").map { it.toInt() }.toMutableList()
    }
    repeat(r) {
        val sub = minOf(n, m) / 2
        repeat(sub) { start ->
            val temp = arr[start][start]
            for (col in start until m - start - 1) {
                arr[start][col] = arr[start][col + 1]
            }
            for (row in start until n - start - 1) {
                arr[row][m - start - 1] = arr[row + 1][m - start - 1]
            }
            for (col in m - start - 1 downTo 1 + start) {
                arr[n - start - 1][col] = arr[n - start - 1][col - 1]
            }
            for (row in n - start - 1 downTo 2 + start) {
                arr[row][start] = arr[row - 1][start]
            }
            arr[1 + start][start] = temp
        }
    }

    for (i in 0 until n) {
        for (j in 0 until m) {
            bw.write("${arr[i][j]} ")
        }
        bw.write("\n")
    }

    br.close()
    bw.close()
}

3. Complexity

• Time : O(r x N), N = min(n, m)
• Space : O(n x m)