Forest Fire

src/Fire.java

@@ -1,3 +1,8 @@
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Queue;
+
 public class Fire {
     /**
      * Returns how long it takes for all vulnerable trees to be set on fire if a
@@ -38,6 +43,56 @@ public class Fire {
     public static int timeToBurn(char[][] forest, int matchR, int matchC) {
         // HINT: when adding to your BFS queue, you can include more information than
         // just a location. What other information might be useful?
-        return -1;
+        boolean[][] visited = new boolean[forest.length][forest[matchR].length];
+        int maxDepth = 0;
+        Queue<int[]> queue = new LinkedList<>();
+
+        if(forest[matchR][matchC] != 't'){
+            return 0;
+        }
+        visited[matchR][matchC] = true;
+        queue.add(new int[] {matchR, matchC, maxDepth});
+
+        while (!queue.isEmpty()) {
+            int[] current = queue.poll();
+            // Math.max shouldn't be necessary but adding it just in case
+            maxDepth = Math.max(maxDepth, current[2]);
+
+            List<int[]> nearby = findAdjacentTrees(forest, visited, current);
+
+            queue.addAll(nearby);
+        }
+
+        return maxDepth;
+    }
+
+    public static List<int[]> findAdjacentTrees(char[][] forest, boolean[][] visited, int[] current) {
+        List<int[]> adjacentTrees = new ArrayList<>();
+        int row = current[0];
+        int col = current[1];
+        int depth = current[2];
+
+        int[][] directions = {
+                {1, 0},
+                {-1, 0},
+                {0, -1},
+                {0, 1}
+        };
+
+        for (int[] direction : directions) {
+            int newR = row + direction[0];
+            int newC = col + direction[1];
+
+            if (newR >= 0  && newR < forest.length && 
+                newC >= 0 &&  newC < forest[0].length &&
+                visited[newR][newC] == false &&
+                forest[newR][newC] == 't') {
+                    visited[newR][newC] = true;
+                    adjacentTrees.add(new int[] { newR, newC, depth + 1 });
+
+                };
+            };
+
+        return adjacentTrees;   
     }
 }

src/FireTest.java

@@ -1,5 +1,9 @@
+import static org.junit.Assert.assertArrayEquals;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
+import java.util.ArrayList;
+import java.util.List;
+
 import org.junit.jupiter.api.Test;
 
 public class FireTest {
@@ -20,4 +24,163 @@ public void testTimeToBurnExample() {
 
         assertEquals(expected, actual);
     }
+
+    @Test 
+    public void testSingleTree() {
+        char[][] forest = {
+            {'.', '.', '.'},
+            {'.', 't', '.'},
+            {'.', '.', '.'}
+        };
+        int matchR = 1;
+        int matchC = 1;
+
+        //one tree burn
+        int expected = 0;  
+        int actual = Fire.timeToBurn(forest, matchR, matchC);
+
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    public void testNoTree(){
+        char[][] forest = {
+            {'.', '.', '.'},
+            {'.', '.', '.'},
+            {'.', '.', '.'}
+        };
+        int matchR = 1;
+        int matchC = 1;
+
+        int expected = 0;  
+        int actual = Fire.timeToBurn(forest, matchR, matchC);
+
+        assertEquals(expected, actual);
+
+    }
+
+     @Test
+    public void testAllTreesConnected() {
+        char[][] forest = {
+            {'t', 't', 't'},
+            {'t', 't', 't'},
+            {'t', 't', 't'}
+        };
+        int matchR = 1;
+        int matchC = 1;
+
+        int expected = 2; 
+        int actual = Fire.timeToBurn(forest, matchR, matchC);
+
+        assertEquals(expected, actual);
+    }
+
+
+
+
+    @Test
+    public void adjacentTrees() {
+        char[][] forest = {
+            {'t','.','.','t','t','t','t','.','t'},
+            {'.','.','t','t','.','.','.','.','t'},
+            {'.','.','t','t','t','t','t','t','t'},
+            {'t','t','t','t','.','.','.','.','.'}
+        };
+
+        int matchR = 2;
+        int matchC = 6;
+
+        int expected = 8;
+        int actual = Fire.timeToBurn(forest, matchR, matchC);
+
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    public void timeToBurn_OneTree() {
+        char[][] forest = {
+            {'t','.'},
+            {'.','.'},
+            {'.','.'},
+            {'t','t'}
+        };
+
+        int matchR = 0;
+        int matchC = 0;
+
+        int expected = 0;
+        int actual = Fire.timeToBurn(forest, matchR, matchC);
+
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    public void timeToBurn_TwoTrees() {
+    char[][] forest = {
+        {'t','.'},
+        {'.','.'},
+        {'.','.'},
+        {'t','t'}
+    };
+
+    int matchR = 3;
+    int matchC = 1;
+
+    int expected = 1;
+    int actual = Fire.timeToBurn(forest, matchR, matchC);
+
+    assertEquals(expected, actual);
+    }
+
+    @Test
+    public void adjacentTrees_TwoTrees() {
+        char[][] forest = {
+            {'t','.'},
+            {'.','.'},
+            {'.','.'},
+            {'t','t'}
+        };
+
+        boolean[][] visited = new boolean[forest.length][forest[0].length];
+
+
+        List<int[]> expected = new ArrayList<>();
+        expected.add(new int[]{3, 0, 1});
+
+        int matchR = 3;
+        int matchC = 1;
+        int depth = 0;
+
+        int[] start = new int[] {matchR, matchC, depth};
+        visited[matchR][matchC] = true;
+
+        List<int[]> nearby = Fire.findAdjacentTrees(forest, visited, start);
+
+        for (int i = 0; i < expected.size(); i++) {
+            assertArrayEquals(expected.get(i), nearby.get(i));
+        }
+    }
+
+    @Test
+    public void adjacentTrees_NoneAdjacent() {
+        char[][] forest = {
+            {'t','.'},
+            {'.','.'},
+            {'.','.'},
+            {'t','t'}
+        };
+
+        boolean[][] visited = new boolean[forest.length][forest[0].length];
+
+        int matchR = 0;
+        int matchC = 0;
+        int depth = 0;
+
+        int[] start = new int[] {matchR, matchC, depth};
+        visited[matchR][matchC] = true;
+
+        List<int[]> nearby = Fire.findAdjacentTrees(forest, visited, start);
+
+        assertEquals(0, nearby.size());
+    }
 }