螺旋矩阵

[louzhedong]

习题

出处：LeetCode 算法第54题

给定一个包含 m x n 个元素的矩阵（m 行, n 列），请按照顺时针螺旋顺序，返回矩阵中的所有元素。

示例 1:

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

示例 2:

输入:
[
  [1, 2, 3, 4],
  [5, 6, 7, 8],
  [9,10,11,12]
]
输出: [1,2,3,4,8,12,11,10,9,5,6,7]

思路

定义四个角四个指针，循环遍历四条边

解答

/**
 * @param {number[][]} matrix
 * @return {number[]}
 */
var spiralOrder = function (matrix) {
  var result = [];
  var row = matrix.length - 1;
  var col = matrix[0].length - 1;
  var r = 0;
  var c = 0;
  while (r <= row && c <= col) {
    for (var i = r; i <= col; i++) {
      result.push(matrix[r][i]);
    }
    r++;
    for (var i = r; i <= row; i++) {
      result.push(matrix[i][col]);
    }
    col--;
    if (r <= row) {
      for (var i = col; i >= c; i--) {
        result.push(matrix[row][i]);
      }
      row--;
    }
    if (c <= col) {
      for (var i = row; i >= r; i--) {
        result.push(matrix[i][c]);
      }
      c++;
    }
  }

  return result;
};

console.log(spiralOrder([
  [1, 2, 3, 4],
  [5, 6, 7, 8],
  [9, 10, 11, 12]
]));

[FFFsssA]

if(matrix.length < 1) {return [];}