矩阵

顺时针打印矩阵

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

let matrix = [
  [1, 2, 3, 4],
  [5, 6, 7, 8],
  [9, 10, 11, 12],
];
let spiralOrder = function (matrix) {
  if (matrix.length === 0 || matrix[0].length === 0) {
    return [];
  }
  let rows = matrix.length, columns = matrix[0].length;
  let left = 0, right = columns - 1, top = 0, bottom = rows - 1;
  let order = [];
  while (left <= right && top <= bottom) {
    for (let column = left; column <= right; column++) {
      order.push(matrix[top][column]);
    }
    for (let row = top + 1; row <= bottom; row++) {
      order.push(matrix[row][right]);
    }
    if (left < right && top < bottom) {
      for (let column = right - 1; column > left; column--) {
        order.push(matrix[bottom][column]);
      }
      for (let row = bottom; row > top; row--) {
        order.push(matrix[row][left]);
      }
    }
    [left, right, top, bottom] = [left + 1, right - 1, top + 1, bottom - 1];
  }
  return order;
};
console.log(spiralOrder(matrix));