ideas
It is to simulate the problem of finding the law: according to the rules of the lower right and upper left
topic
Enter a matrix and print each number in clockwise order from the outside to the inside.
Sample
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]
java code
class Solution {
public int[] printMatrix(int[][] matrix) {
int res[] = {
};
int n = matrix.length;
if (n == 0) return res;
int m = matrix[0].length;
Boolean st[][] = new Boolean[n][m];
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
st[i][j] = false;
}
}
res = new int[n * m];
int dx[] = {
0, 1, 0, -1}, dy[] = {
1, 0, -1, 0};
int x = 0, y = 0, d = 0;
for (int i = 0; i < n * m; i++) {
res[i] = matrix[x][y];
st[x][y] = true;
int a = x + dx[d], b = y + dy[d];
if (a < 0 || a >= n || b < 0 || b >= m || st[a][b]) {
d = (d + 1) % 4;
a = x + dx[d];
b = y + dy[d];
}
x = a;
y = b;
}
return res;
}
}