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]这个题目很简单,上下左右分别用四个变量去标志: 上:top 下:bottom 左:left 右: right
就按照四步走就可以: 1. left -> right 2. top -> bottom 3. right -> left 4. bottom -> top
每一步走完要对边界做出调整,具体看代码吧,清晰易懂。
class Solution { public List<Integer> spiralOrder(int[][] matrix) { List<Integer> res = new ArrayList<Integer>(); if (matrix.length == 0 || matrix[0].length == 0) return res; int top = 0; int bottom = matrix.length - 1; int left = 0; int right = matrix[0].length - 1; while (true) { for (int i = left; i <= right; i++) res.add(matrix[top][i]); top++; if (left > right || top > bottom) break; for (int i = top; i <= bottom; i++) res.add(matrix[i][right]); right--; if (left > right || top > bottom) break; for (int i = right; i >= left; i--) res.add(matrix[bottom][i]); bottom--; if (left > right || top > bottom) break; for (int i = bottom; i >= top; i--) res.add(matrix[i][left]); left++; if (left > right || top > bottom) break; } return res; } }