Add coding exercises for Facebook interviews

Add attempts at solving coding problems to Briefcase.

scratch/facebook/utils.py

@@ -0,0 +1,19 @@
+def init_table(rows=0, cols=0, default=None):
+    table = []
+    for row in range(rows):
+        x = []
+        for col in range(cols):
+            x.append(default)
+        table.append(x)
+    return table
+
+def get(table, row, col, default=0):
+    if row < 0 or col < 0:
+        return default
+    return table[row][col]
+
+def print_table(table):
+    result = []
+    for row in range(len(table)):
+        result.append(' '.join([str(cell) for cell in table[row]]))
+    print('\n'.join(result))