使用递归,但效率很低
class Solution {
public List<Integer> spiralOrder(int[][] matrix) {
if (matrix == null || matrix.length == 0 || matrix[0].length == 0)
return new ArrayList<>();
ArrayList<Integer> reseult = new ArrayList<>(matrix.length * matrix[0].length);
dfs(0, 0, matrix, new boolean[matrix.length][matrix[0].length], reseult);
return reseult;
}
public void dfs(int x, int y, int[][] matrix, boolean[][] over, ArrayList<Integer> reseult) {
if (check(x, y, matrix, over)) {
over[x][y] = true;
reseult.add(matrix[x][y]);
dfs(x, y + 1, matrix, over, reseult);
dfs(x + 1, y, matrix, over, reseult);
dfs(x, y - 1, matrix, over, reseult);
xdown(x - 1, y, matrix, over, reseult);
}
}
public boolean check(int x, int y, int[][] matrix, boolean[][] over) {
if ((x | y | (matrix.length - x - 1) | (matrix[0].length - y - 1)) < 0 || over[x][y])
return false;
return true;
}
public void xdown(int x, int y, int[][] matrix, boolean[][] over, ArrayList<Integer> reseult) {
while (check(x - 1, y, matrix, over)) {
over[x][y] = true;
reseult.add(matrix[x][y]);
--x;
}
dfs(x, y, matrix, over, reseult);
}
}