Implemented methods in SalamanderSearch

src/SalamanderSearch.java

@@ -1,5 +1,5 @@
 import java.util.ArrayList;
-import java.util.List;
+import java.util.*;
 
 public class SalamanderSearch {
     public static void main(String[] args) {
@@ -18,6 +18,18 @@ public static void main(String[] args) {
             {'f','W','.','.','W','.'},
             {'W','.','W','.','.','.'},
         };
+
+        Set<int[]> coordinateSet = new HashSet<>();
+        int[] coord1 = new int[]{1, 5};
+        int[] coord2 = new int[]{3, 7};
+        int[] coord3 = new int[]{1, 5};
+
+        coordinateSet.add(coord1);
+        coordinateSet.add(coord2);
+        coordinateSet.add(coord3);
+
+        System.out.println(coordinateSet.size());
+
     }
 
     /**
@@ -43,6 +55,79 @@ 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<>();
+
+         int[][] directions = new int[][] {
+            {-1, 0},
+            {1, 0},
+            {0, -1},
+            {0, 1}
+         };
+
+         for (int[] direction: directions) {
+            int newRow = currentRow + direction[0];
+            int newCol = currentCol + direction[1];
+
+            // Note that the below check can also be moved to an isValid helper function
+
+            if (newRow >= 0 && newRow < enclosure.length && 
+                newCol >= 0 && newCol < enclosure[0].length &&
+                enclosure[newRow][newCol] != 'W') {
+                    moves.add(new int[]{newRow, newCol});
+                }
+         }
+
+         return moves;
+
+    }
 }