剑指 Offer 29. 顺时针打印矩阵-简单

难度：简单

题目描述：
输入一个矩阵，按照从外向里以顺时针的顺序依次打印出每一个数字

示例：

输入：matrix = [[1,2,3],[4,5,6],[7,8,9]]
输出：[1,2,3,6,9,8,7,4,5]

解题思路：

var spiralOrder = function (matrix) {
  if (matrix.length == 0) return []
  const res = []
  let top = 0, bottom = matrix.length - 1, left = 0, right = matrix[0].length - 1
  const size = matrix.length * matrix[0].length
  while (res.length !== size) { // 仍未遍历结束
    for (let i = left; i <= right; i++) res.push(matrix[top][i])
    top++
    for (let i = top; i <= bottom; i++) res.push(matrix[i][right])
    right--
    if (res.length === size) break // 遍历结束
    for (let i = right; i >= left; i--)  res.push(matrix[bottom][i])
    bottom--
    for (let i = bottom; i >= top; i--) res.push(matrix[i][left])
    left++
  }
  return res
};

var spiralOrder = function (matrix) {
  if (matrix.length == 0) return []
  const res = []
  let top = 0, bottom = matrix.length - 1, left = 0, right = matrix[0].length - 1
  while (top <= bottom && left <= right) {
    for (let i = left; i <= right; i++) res.push(matrix[top][i])
    top++
    for (let i = top; i <= bottom; i++) res.push(matrix[i][right])
    right--
    if (top > bottom || left > right) break
    for (let i = right; i >= left; i--) res.push(matrix[bottom][i])
    bottom--
    for (let i = bottom; i >= top; i--) res.push(matrix[i][left])
    left++
  }
  return res
};