标签：list put input color turn 原来 order 从右到左 lis
Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.
Example 1:
Input: [ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ] ] Output: [1,2,3,6,9,8,7,4,5]
Example 2:
Input: [ [1, 2, 3, 4], [5, 6, 7, 8], [9,10,11,12] ] Output: [1,2,3,4,8,12,11,10,9,5,6,7]
思路很简单，整个输出过程用rowLowerBound,rowUpperBound,colLowerBound,colUpperBound来控制边界。输出时要控制边界缩小，并且输出的内容要在边界内。
几种特殊情况：
{1,2,3,4},
{5,6,7,8},
{9,10,11,12}
{1,2,3},
{4,5,6},
{7,8,9}
{1 , 2, 3, 4, 5},
{6, 7, 8 ,9,10},
{11,12,13,14,15},
{16,17,18,19,20},
{21,22,23,24,25}
{ 1, 2, 3, 4, 5, 6},
{ 7, 8, 9,10,11,12},
{13,14,15,16,17,18},
{19,20,21,22,23,24}
{6,9,7}
{1},
{2},
{3}
{1,2},
{3,4},
{5,6},
{7,8}
1 class Solution { 2 public List<Integer> spiralOrder(int[][] matrix) { 3 int row, col; 4 row = matrix.length; 5 ArrayList<Integer> list = new ArrayList<>(); 6 if (row == 0) 7 return list; 8 col = matrix[0].length; 9 10 /* 11 只能在边界内循环 12 */ 13 int rowLowerBound = 0, rowUpperBound = row-1; 14 int colLowerBound = 0, colUpperBound = col-1; 15 while (rowLowerBound <= rowUpperBound && colLowerBound <= colUpperBound){ 16 /* 17 沿着行rowLowerBound从左至右输出 18 沿着列colUpperBound从上到右输出 19 沿着行rowUpperBound从右到左输出 20 沿着列colLowerBound从下到上输出 21 22 变更边界条件（转向内层矩阵，等于是将原来矩阵剥了一层皮） 23 rowLowerBound+1, rowUpperBound-1, colLowerBound+1,colUpperBound-1 24 */ 25 for (int i = colLowerBound, flag = 1; i < colUpperBound; i++) {//→ 26 list.add(matrix[rowLowerBound][i]); 27 if (rowLowerBound == rowUpperBound){ 28 ++colLowerBound; 29 }else if(colLowerBound < colUpperBound && flag == 1 && rowUpperBound != row-1){ 30 ++colLowerBound; 31 flag = 0; 32 } 33 } 34 for (int i = rowLowerBound, flag = 1; i < ((rowUpperBound == 0) ? 1 : rowUpperBound); i++) {//↓ 35 list.add(matrix[i][colUpperBound]); 36 37 if (colLowerBound == colUpperBound){ 38 ++rowLowerBound; 39 }else if(rowLowerBound < rowUpperBound && flag == 1) { 40 ++rowLowerBound; 41 flag = 0; 42 } 43 } 44 for (int i = colUpperBound, flag = 1; i > colLowerBound; i--) {//← 45 list.add(matrix[rowUpperBound][i]); 46 if(rowLowerBound == rowUpperBound) 47 --colUpperBound; 48 else if (colLowerBound < colUpperBound && flag == 1){ 49 --colUpperBound; 50 flag = 0; 51 } 52 } 53 for (int i = rowUpperBound, flag = 1; i > rowLowerBound; i--) {//↑ 54 list.add(matrix[i][colLowerBound]); 55 if (colLowerBound == colUpperBound) 56 --rowUpperBound; 57 else if (rowLowerBound < rowUpperBound && flag == 1){ 58 --rowUpperBound; 59 flag = 0; 60 } 61 } 62 if (rowLowerBound == rowUpperBound && colLowerBound == colUpperBound){ 63 list.add(matrix[rowLowerBound][colLowerBound]); 64 break; 65 } 66 } 67 return list; 68 } 69 }
标签：list put input color turn 原来 order 从右到左 lis
原文地址：https://www.cnblogs.com/yfs123456/p/10888055.html
