Completed SalamanderSearch.java

src/SalamanderSearch.java

@@ -43,6 +43,87 @@ public static void main(String[] args) {
      * @return whether the salamander can reach the food
      */
     public static boolean canReach(char[][] enclosure) {
+        // find salamander
+        int[] start = salamanderLocation(enclosure);
+        // this boolean is the same size as the enclosure and starts off all false by default
+        boolean[][] visited = new boolean[enclosure.length][enclosure[0].length];
+
+        // recursive dfs
+        return canReach(enclosure, start, visited);
+    }
+
+    /* Helper method that passes in current location and boolean record of visited locations. */
+    public static boolean canReach(char[][] enclosure, int[] current, boolean[][] visited) {
+        int currRow = current[0];
+        int currCol = current[1];
+
+        if (visited[currRow][currCol]) return false;
+        if (enclosure[currRow][currCol] == 'f') return true;
+
+        visited[currRow][currCol] = true;
+
+        List<int[]> moves = possibleMoves(enclosure, current);
+
+        for (var move: moves) {
+            if (canReach(enclosure, move, visited)) return true;
+        }
+
         return false;
     }
+
+
+    /* Helper method to find salamander starting position.
+    Returns an array of integers that represent the row and column of the starting position of the salamander */
+    public static int[] salamanderLocation(char[][] enclosure) {
+        for (int r = 0; r < enclosure.length; r++) {
+            for (int c = 0; c < enclosure[r].length; c++) {
+                if (enclosure[r][c] == 's') {
+                    return new int[]{r, c};
+                }
+            }
+        }
+        throw new IllegalArgumentException("No salamander present");
+    }
+
+    /* Helper method
+     * Given a current location, what are the possible valid moves
+     * Checks up, down, left, right
+     */
+    public static List<int[]> possibleMoves(char[][] enclosure, int[] currentLocation) {
+        int currentRow = currentLocation[0];
+        int currentCol = currentLocation[1];
+
+        List<int[]> moves = new ArrayList<>();
+
+        // UP
+        int newRow = currentRow - 1;
+        int newCol = currentCol;
+        if (newRow >= 0 && enclosure[newRow][newCol] != 'W') {
+            moves.add(new int[]{newRow, newCol});
+        }
+
+        // DOWN
+        newRow = currentRow + 1;
+        newCol = currentCol;
+        if (newRow < enclosure.length && enclosure[newRow][newCol] != 'W') {
+            moves.add(new int[]{newRow, newCol});
+        }
+
+        // LEFT
+        newRow = currentRow;
+        newCol = currentCol - 1;
+        if (newCol >= 0 && enclosure[newRow][newCol] != 'W') {
+            moves.add(new int[]{newRow, newCol});
+        }
+
+        // RIGHT
+        newRow = currentRow;
+        newCol = currentCol + 1;
+        if (newCol < enclosure[0].length && enclosure[newRow][newCol] != 'W') {
+            moves.add(new int[]{newRow, newCol});
+        }
+
+        return moves;
+    }
+
 }