(#286)WallsandGates

Author: FeiCoding

(#286)WallsandGates/WallsandGates.java

@@ -0,0 +1,35 @@
+class Solution {
+    public void wallsAndGates(int[][] rooms) {
+        if(rooms.length <= 0 || rooms[0].length <= 0) return;
+        Queue<int []> queue = new LinkedList<>();
+        for(int i = 0; i < rooms.length; i++){
+            for(int j = 0; j < rooms[0].length; j++){
+                if(rooms[i][j] == 0)
+                    queue.add(new int[]{i, j});
+            }
+        }
+        
+        while(!queue.isEmpty()){
+            int index[] = queue.poll();
+            int row = index[0];
+            int col = index[1];
+            if(row > 0 && rooms[row - 1][col] == Integer.MAX_VALUE){
+                rooms[row - 1][col] = rooms[row][col] + 1;
+                queue.add(new int[]{row - 1, col});
+            }
+            if(row < rooms.length - 1 && rooms[row + 1][col] == Integer.MAX_VALUE){
+                rooms[row + 1][col] = rooms[row][col] + 1;
+                queue.add(new int[]{row + 1, col});
+            }
+            
+            if(col > 0 && rooms[row][col - 1] == Integer.MAX_VALUE){
+                rooms[row][col - 1] = rooms[row][col] + 1;
+                queue.add(new int[]{row, col - 1});
+            }
+            if(col < rooms[0].length - 1 && rooms[row][col + 1] == Integer.MAX_VALUE){
+                rooms[row][col + 1] = rooms[row][col] + 1;
+                queue.add(new int[]{row, col + 1});
+            }
+        }
+    }
+}