Finished BFS methods

src/Search.java

@@ -1,3 +1,8 @@
+import java.util.List;
+import java.util.ArrayList;
+import java.util.Queue;
+import java.util.LinkedList;
+
 public class Search {
      /**
      * Finds the location of the nearest reachable cheese from the rat's position.
@@ -29,6 +34,105 @@ public class Search {
      * @throws HungryRatException if there is no reachable cheese
      */
     public static int[] nearestCheese(char[][] maze) throws EscapedRatException, CrowdedMazeException, HungryRatException {
-        return null;
+        boolean[][] visited = new boolean[maze.length][maze[0].length];
+        int[] start = ratLocation(maze);
+
+        // queue = []
+        Queue<int[]> queue = new LinkedList<>();
+        // qeueu.add(start);
+        queue.add(start);
+
+        // while queue != empty
+        while (!queue.isEmpty()) {
+        //  current = queue.pop
+        int[] current = queue.poll();
+        //  if visited: continue
+        int curR = current[0];
+        int curC = current[1];
+
+        // if visited : continue
+        if (visited[curR][curC]) {
+            continue;
+        }
+
+        //   mark visited
+        visited[curR][curC] = true;
+        //  if current is cheese: return current
+        if (maze[curR][curC] == 'c') {
+            return current;
+        }
+
+        queue.addAll(getNeighbors(maze, current));
+    }
+
+        // return hungee
+    throw new HungryRatException();
+
+    }
+
+
+
+    public static List<int[]> getNeighbors (char[][] maze, int[] current) {
+        int currR = current[0];
+        int currC = current[1];
+
+        // UP    [-1, 0]
+        // DOWN  [1,0]
+        // left  [0, -1]
+        // right [0,1]
+
+        int[][] directions = {
+            {-1,0}, // up
+            {1,0}, // down4
+            {0,-1}, // left
+            {0,1} // right
+        };
+
+        List<int[]> possibleMoves = new ArrayList<>();
+
+        for (int[] direction : directions) {
+            int changeR = direction[0];
+            int changeC = direction[1];
+
+            int newR = currR + changeR;
+            int newC = currC + changeC;
+
+            if (newR >= 0 && newR < maze.length && 
+                newC >= 0 && newC < maze[newR].length 
+                && maze[newR][newC] != 'w') {
+                    // valid move!
+                    int[] validMove = {newR, newC};
+                    possibleMoves.add(validMove);
+            }
+
+        }
+        return possibleMoves;
+    }
+
+    public static int[] ratLocation(char[][] maze) throws EscapedRatException, CrowdedMazeException {
+        int[]  location = null;
+
+        // Searching
+        for (int r = 0; r < maze.length; r++) {
+            for (int c = 0; c < maze[r].length; c++) {
+                if (maze[r][c] == 'R') {
+                    if (location != null) {
+                        throw new CrowdedMazeException();
+                    }
+
+                    location = new int[]{r, c};
+                }
+            }
+        }
+
+        if (location == null) {
+            // 404 rat not found
+            throw new EscapedRatException();
+        }
+        return location;
+    }
+
+    public static void main(String[] args) {
+
     }
 }