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]
根据题意就是螺旋读取结果值:(注意一些情况 会重复读取)
public List<Integer> spiralOrder(int[][] matrix) {
List<Integer> res = new ArrayList<>();
if(matrix == null || matrix.length == 0 ) {
return res;
}
getRes(0,0,res,matrix);
return res;
}
public void getRes(int beginI, int beginJ, List<Integer> res, int[][] matrix) {
int i = beginI;
int j = beginJ;
if(i>= matrix.length-beginI || j >=matrix[i].length-beginJ ) {
return;
}
res.add(matrix[i][j]);
boolean right = false;
while (j < matrix[i].length - beginJ - 1) {
res.add(matrix[i][++j]);
right = true;
}
while (i < matrix.length - beginI - 1 ) {
res.add(matrix[++i][j]);
}
while (j > beginJ && i!= beginI) {
res.add(matrix[i][--j]);
}
while(i > beginI+1 && j == beginJ && right) {
res.add(matrix[--i][j]);
}
if (i > beginI && j == beginJ ) {
getRes(beginI + 1, beginJ + 1, res, matrix);
}
}