题目：
题解：
按层 计算
const spiralOrder = function(matrix) {let rows = matrix.length;let cols = matrix[0].length;let res = [];//特殊情况if(rows === 0 || cols === 0) return res;if(rows === 1) return matrix[0];//设置每层的边界 let left = 0, right = cols - 1, top = 0, bottom = rows - 1;while(left<= right && top <= bottom){//从左到右for(let i = left; i <= right; i++){res.push(matrix[top][i]);}//从上到下for(let i = top + 1; i <= bottom; i++){res.push(matrix[i][right]);}//若该层完整，能四周走一圈if(top < bottom && left < right){//从右到左for(let i = right - 1; i >= left; i--){res.push(matrix[bottom][i]);}//从下到上 for(let i = bottom - 1; i > top; i--){res.push(matrix[i][left]);}}//改变边界left++;right--;top++;bottom--;}return res;
}
