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| class Solution {
private static final int[][] DIRECTIONS = new int[][]{{1, 2}, {1, -2}, {-1, 2}, {-1, -2}, {2, 1}, {2, -1}, {-2, 1}, {-2, -1}};
public boolean checkValidGrid(int[][] grid) {
return dfs(grid, 0, 0, 0);
}
private boolean dfs(int[][] grid, int i, int j, int excepted) {
int m = grid.length, n = grid[0].length;
if (grid[i][j] != excepted) {
return false;
}
if (excepted == m * n - 1) {
return true;
}
for (int[] direction : DIRECTIONS) {
int nextI = i + direction[0], nextJ = j + direction[1];
if (nextI >= 0 && nextI < m && nextJ >= 0 && nextJ < n) {
if (dfs(grid, nextI, nextJ, excepted + 1)) {
return true;
}
}
}
return false;
}
}
|