Explorer homework

src/ExplorerSearch.java

@@ -32,6 +32,91 @@ public static int reachableArea(int[][] island) {
         // Implement your method here!
         // Please also make more test cases
         // I STRONGLY RECOMMEND testing some helpers you might make too
-        return -1;
+        int[] start = explorerLocation(island);
+        boolean[][] visited = new boolean[island.length][island[0].length];
+        return reachableArea(island, start, visited);
+    }
+
+    public static int reachableArea(int[][] island, int[] current, boolean[][] visited) {
+        int curR = current[0];
+        int curC = current[1];
+
+        // if we've been here before, return 0
+        if (visited[curR][curC]) return 0;
+
+        // if we haven't, count the current space and set visited to true
+        int spaces = 1;
+        visited[curR][curC] = true;
+
+        // find the list of where we can get to from here
+        List<int[]> neighbors = possibleMoves(island, current);
+
+        // go through the list
+        for (int[] neighbor : neighbors) {
+            //add the results to our number of valid spaces
+            spaces += reachableArea(island, neighbor, visited);
+        }
+
+        // send the list back to top
+        // after we run out of valid spaces, this should return the final result to the top level
+        return spaces;
+    }
+
+    public static int[] explorerLocation(int[][] island) {
+        //go through the area and find the explorer
+        for (int r=0; r < island.length; r++) {
+            for (int c = 0; c < island[r].length; c++) {
+                if (island[r][c] == 0) {
+                    int[] location = new int[] {r, c};
+                    return location;
+                }
+            }
+        }
+
+       // you didn't give explicit instructions for a missing explorer so I am doing it the same as on the live code assignment
+
+       // if this was an undesirable result, a missing explorer could also set the start location out of bounds {-1, -1} with a check that returns 0 total moves for that starting location (if there's no explorer on the island, 0 "squares" are explorable)
+       throw new IllegalArgumentException("No explorer on the island.");
+    }
+
+    public static List<int[]> possibleMoves(int[][] island, int[] current) {
+        List<int[]> moves = new ArrayList<>();
+
+        int curR = current[0];
+        int curC = current[1];
+
+
+        // up
+        int newR = curR - 1;
+        int newC = curC;
+
+        if (newR >= 0 && island[newR][newC] == 1) {
+            moves.add(new int[]{newR, newC});
+        }
+
+        // down
+        newR = curR + 1;
+        newC = curC;
+
+        if (newR < island.length && island[newR][newC] == 1) {
+            moves.add(new int[]{newR, newC});
+        }
+        // left
+        newR = curR;
+        newC = curC - 1;
+
+        if (newC >= 0 && island[newR][newC] == 1) {
+            moves.add(new int[] {newR, newC});
+        }
+
+        // right
+        newR = curR;
+        newC = curC + 1;
+
+        if (newC < island[newR].length && island[newR][newC] == 1) {
+            moves.add(new int[] {newR, newC});
+        }
+
+        return moves;
     }
 }