Merge pull request #2471 from leahjia/1091-shortest-path-in-binary-matrix

Create: 1091-shortest-path-in-binary-matrix.java

Author: MHamiid

Diff for: java/1091-shortest-path-in-binary-matrix.java

@@ -0,0 +1,35 @@
+class Solution {
+  public int shortestPathBinaryMatrix(int[][] grid) {
+    int n = grid.length;
+    Queue<Integer[]> q = new LinkedList<>();
+    q.add(new Integer[]{0, 0, 1}); // row, col, length
+    
+    boolean[][] visited = new boolean[n][n];
+    visited[0][0] = true;
+    
+    int[][] direct = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}, {1, 1}, {-1, -1}, {1, -1}, {-1, 1}};
+
+    while (!q.isEmpty()) {
+      Integer[] curr = q.poll();
+      int r = curr[0];
+      int c = curr[1];
+      int length = curr[2];
+      
+      // out of bounds or no way further
+      if (Math.min(r, c) < 0 || Math.max(r, c) == n || grid[r][c] == 1) continue;
+      
+      if (r == n - 1 && c == n - 1) return length;
+      
+      for (int[] d : direct) {
+        int newRow = r + d[0];
+        int newCol = c + d[1];
+        if (Math.min(newRow, newCol) >= 0 && Math.max(newRow, newCol) < n && !visited[newRow][newCol]) {
+          q.add(new Integer[]{newRow, newCol, 1 + length});
+          visited[newRow][newCol] = true;
+        }
+      }
+    }
+    return -1;
+  }
+  
+}