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| class Solution {
private int[][] directions = new int[][] { { -1, 0 }, { -1, -1 }, { 0, -1 }, { 1, -1 }, { 1, 0 }, { 1, 1 },
{ 0, 1 }, { -1, 1 } };
public int shortestPathBinaryMatrix(int[][] grid) {
if (grid[0][0] == 1) {
return -1;
}
if (grid.length == 1) {
return 1;
}
int n = grid.length;
boolean[][] visited = new boolean[n][n];
Deque<int[]> q = new ArrayDeque<>();
q.offer(new int[] { 0, 0 });
visited[0][0] = true;
int steps = 1;
while (!q.isEmpty()) {
for (int i = q.size(); i > 0; i--) {
int[] currPos = q.poll();
for (int[] direction : directions) {
int newRow = currPos[0] + direction[0];
int newCol = currPos[1] + direction[1];
if (!isOutOfBound(n, newRow, newCol) && grid[newRow][newCol] == 0 && !visited[newRow][newCol]) {
if (newRow == n - 1 && newCol == n - 1) {
return steps + 1;
}
q.offer(new int[] { newRow, newCol });
visited[newRow][newCol] = true;
}
}
}
steps += 1;
}
return -1;
}
private boolean isOutOfBound(int n, int row, int col) {
return row < 0 || row >= n || col < 0 || col >= n;
}
}
|
