54. 螺旋矩阵

解法：按层模拟

思路：这题并不难，选择一个好理解的思路进行练习即可。

这个思路主要是这张图：（来自LeetCode官方题解）

详细请移步：https://leetcode-cn.com/problems/spiral-matrix/solution/luo-xuan-ju-zhen-by-leetcode-solution/

class Some54Solution {

    fun spiralOrder(matrix: Array<IntArray>): List<Int> {
        if (matrix.isEmpty()) return arrayListOf()
        val rows = matrix.size
        val columns = matrix[0].size
        var left = 0
        var right = columns - 1
        var top = 0
        var bottom = rows - 1

        val res = arrayListOf<Int>()
        while (left <= right && top <= bottom) {
            for (column in left..right) {
                res.add(matrix[top][column])
            }
            for (row in top + 1..bottom) {
                res.add(matrix[row][right])
            }
            if (left < right && top < bottom) {
                for (column in right - 1 downTo left) {
                    res.add(matrix[bottom][column])
                }
                for (row in bottom - 1 downTo top + 1) {
                    res.add(matrix[row][left])
                }
            }
            left++
            right--
            top++
            bottom--
        }
        return res
    }

}

fun main() {
    val array = arrayOf(
        intArrayOf(1,   2,  3, 4),
        intArrayOf(12, 13, 14, 5),
        intArrayOf(11, 16, 15, 6),
        intArrayOf(10,  9,  8, 7)
    )
    Some54Solution().spiralOrder(array).forEach {
        print("$it ")
    }
}