in class DFS matrix assignment

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+    "githubPullRequests.ignoredPullRequestBranches": [
+        "main"
+    ]
+}

src/SalamanderSearch.java

@@ -1,23 +1,36 @@
-import java.util.ArrayList;
-import java.util.List;
+import java.util.*;
 
 public class SalamanderSearch {
     public static void main(String[] args) {
         char[][] enclosure1 = {
-            {'.','.','.','.','.','.'},
-            {'W','.','W','W','.','.'},
-            {'.','.','W','.','.','W'},
-            {'f','W','.','.','W','.'},
-            {'W','.','W','s','.','.'},
+                { '.', '.', '.', '.', '.', '.' },
+                { 'W', '.', 'W', 'W', '.', '.' },
+                { '.', '.', 'W', '.', '.', 'W' },
+                { 'f', 'W', '.', '.', 'W', '.' },
+                { 'W', '.', 'W', 's', '.', '.' },
         };
 
         char[][] enclosure2 = {
-            {'.','.','.','.','.','.'},
-            {'W','W','W','W','s','.'},
-            {'.','.','W','.','.','W'},
-            {'f','W','.','.','W','.'},
-            {'W','.','W','.','.','.'},
+                { '.', '.', '.', '.', '.', '.' },
+                { 'W', 'W', 'W', 'W', 's', '.' },
+                { '.', '.', 'W', '.', '.', 'W' },
+                { '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);
+
+        // the actual contents are not what's been added, it's the references to each
+        // variable that's added!
+        System.out.println(coordinateSet.size());
+
     }
 
     /**
@@ -43,6 +56,97 @@ public static void main(String[] args) {
      * @return whether the salamander can reach the food
      */
     public static boolean canReach(char[][] enclosure) {
+        int[] start = salamanderLocation(enclosure);
+        boolean[][] visited = new boolean[enclosure.length][enclosure[0].length];
+        return canReach(enclosure, start, visited);
+    }
+
+    public static boolean canReach(char[][] enclosure, int[] current, boolean[][] visited) {
+
+        int curR = current[0];
+        int curC = current[1];
+
+        // base case already been there
+        if (visited[curR][curC])
+            return false;
+        // base case found food
+        if (enclosure[curR][curC] == 'f')
+            return true;
+
+        visited[curR][curC] = true;
+
+        List<int[]> moves = possibleMoves(enclosure, current);
+        for (int[] move : moves) {
+            if (canReach(enclosure, move, visited))
+                return true;
+        }
         return false;
     }
+
+    // int array holds {row,col} location of sal
+    public static int[] salamanderLocation(char[][] enclosure) {
+        // base case if array null auto produces NPE
+        for (int r = 0; r < enclosure.length; r++) {
+            for (int c = 0; c < enclosure[0].length; c++) {
+                if (enclosure[r][c] == 's') {
+                    return new int[] { r, c };
+                }
+            }
+        }
+        throw new IllegalArgumentException("No salamander present");
+    }
+
+    public static List<int[]> possibleMoves(char[][] enclosure, int[] current) {
+        int curR = current[0];
+        int curC = current[1];
+
+        List<int[]> moves = new ArrayList<>();
+
+        int[][] directions = new int[][] {
+                { -1, 0 },
+                { 1, 0 },
+                { 0, -1 },
+                { 0, 1 }
+        };
+
+        for (int[] direction : directions) {
+            int newR = curR + direction[0];
+            int newC = curC + direction[1];
+            if (newR >= 0 && newR < enclosure.length &&
+                newC >= 0 && newC < enclosure[0].length &&
+                enclosure[newR][newC] != 'W') {
+                    moves.add(new int[] { newR, newC });
+            }
+
+        }
+
+        // // UP
+        // int newR = curR - 1;
+        // int newC = curC;
+        // if(newR >= 0 && enclosure[newR][newC] != 'W') {
+        // moves.add(new int[]{newR, newC});
+        // }
+
+        // // DOWN
+        // newR = curR + 1;
+        // newC = curC;
+        // if(newR < enclosure.length && enclosure[newR][newC] != 'W') {
+        // moves.add(new int[]{newR, newC});
+        // }
+
+        // // LEFT
+        // newR = curR;
+        // newC = curC - 1;
+        // if(newC >= 0 && enclosure[newR][newC] != 'W') {
+        // moves.add(new int[]{newR, newC});
+        // }
+
+        // // RIGHT
+        // newR = curR;
+        // newC = curC + 1;
+        // if(newC < enclosure[0].length && enclosure[newR][newC] != 'W') {
+        // moves.add(new int[]{newR, newC});
+        // }
+        return moves;
+    }
 }