054. Spiral Matrix.js

var assert = require('assert')
/**
 * @param {number[][]} matrix
 * @return {number[]}
 */
var spiralOrder = function (matrix) {
  if (!matrix || !matrix[0]) return []
  var m = matrix.length,
    n = matrix[0].length

  var _sprial = function (r) {
    var top = [], right = [], bottom = [], left = [], i

    if (2 * r >= m || 2 * r >= n) {
      return []
    }

    for (i = r; i < n - 1 - r; i++) {
      top.push(matrix[r][i])
      bottom.unshift(matrix[m - 1 - r][1 + i])
    }

    for (i = r; i < m - 1 - r; i++) {
      right.push(matrix[i][n - 1 - r])
      left.unshift(matrix[1 + i][r])
    }

    if (2 * r === m - 1) {
      return top.concat(matrix[r][n - 1 - r])
    }

    if (2 * r === n - 1) {
      return right.concat(matrix[m - 1 - r][r])
    }



    return Array().concat(top, right, bottom, left, _sprial(r + 1))
  }
  return _sprial(0)
};

assert.deepEqual(spiralOrder([[1, 2, 3], [4, 5, 6], [7, 8, 9]]), [1, 2, 3, 6, 9, 8, 7, 4, 5])
assert.deepEqual(spiralOrder([[1, 2, 3, 4], [4, 5, 6, 7], [7, 8, 9, 10]]), [1, 2, 3, 4, 7, 10, 9, 8, 7, 4, 5, 6])
assert.deepEqual(spiralOrder([[1, 2, 3, 4], [4, 5, 6, 7], [7, 8, 9, 10], [7, 8, 9, 10]]), [1, 2, 3, 4, 7, 10, 10, 9, 8, 7, 7, 4, 5, 6, 9, 8])
assert.deepEqual(spiralOrder([[1, 2], [4, 5], [7, 8], [9, 8], [7, 8]]), [1, 2, 5, 8, 8, 8, 7, 9, 7, 4])
assert.deepEqual(spiralOrder([[1], [2], [3], [4], [5]]), [1, 2, 3, 4, 5])
assert.deepEqual(spiralOrder([[1, 2, 3, 4, 5]]), [1, 2, 3, 4, 5])
assert.deepEqual(spiralOrder([[]]), [])
assert.deepEqual(spiralOrder([]), [])
assert.deepEqual(spiralOrder([[1]]), [1])
assert.deepEqual(spiralOrder([[1, 2], [3, 4]]), [1, 2, 4, 3])
assert.deepEqual(spiralOrder([[2, 5], [8, 4], [0, -1]]), [2, 5, 4, -1, 0, 8])
assert.deepEqual(spiralOrder([[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]]), [1, 2, 3, 4, 5, 6, 7, 8, 9, 10])