Complete BFS-2-1

EmployeeImportance.java

@@ -0,0 +1,36 @@
+import java.util.*;
+
+// BFS O(n) time, O(n) space
+class Solution {
+    public int getImportance(List<Employee> employees, int id) {
+        Map<Integer, Employee> map = new HashMap<>();
+
+        for (Employee emp : employees) {
+            map.put(id, emp);
+        }
+
+        int ans = 0;
+
+        Queue<Employee> q = new LinkedList<>();
+        q.offer(map.get(id));
+
+        while (!q.isEmpty()) {
+            Employee curr = q.poll();
+
+            ans += curr.importance;
+
+            for (int subId : curr.subordinates) {
+                q.offer(map.get(subId));
+            }
+        }
+        return ans;
+    }
+}
+
+
+// Definition for Employee.
+class Employee {
+    public int id;
+    public int importance;
+    public List<Integer> subordinates;
+};

RottingOranges.java

@@ -0,0 +1,49 @@
+import java.util.*;
+
+// BFS O(m * n) time, O(m * n) space
+class Solution {
+    public int orangesRotting(int[][] grid) {
+        int n = grid.length;
+        int m = grid[0].length;
+        int[][] dirs = new int[][] {
+            {0,1}, {1,0}, {-1,0}, {0,-1}
+        };
+
+        Queue<int[]> q = new LinkedList<>();
+
+        int freshCount = 0;
+        for (int i = 0; i < n; i++) {
+            for (int j = 0; j < m; j++) {
+                if (grid[i][j] == 2) {
+                    q.offer(new int[] {i, j});
+                }
+                else if (grid[i][j] == 1) {
+                    freshCount++;
+                }
+            }
+        }
+
+        int time = 0;
+        while (!q.isEmpty()) {
+            int size = q.size();
+
+            for (int i = 0; i < size; i++) {
+                int[] curr = q.poll();
+                for (int[] dir : dirs) {
+                    int r = curr[0] + dir[0];
+                    int c = curr[1] + dir[1];
+
+                    if (r >= 0 && c >= 0 && r < n && c < n && grid[r][c] == 1) {
+                        q.offer(new int[] {r, c});
+                        grid[r][c] = 2; // mark rotten
+                        freshCount--;
+                    }
+                }
+            }
+            time++; // increment time after each level
+        }
+        if (freshCount == 0) return time-1;
+
+        return -1;
+    }
+}