Add coding exercises for Facebook interviews

Add attempts at solving coding problems to Briefcase.

scratch/facebook/merge-sorted-arrays.py

@@ -0,0 +1,44 @@
+def merge_sorted(xs, ys):
+    result = []
+    i, j = 0, 0
+
+    while i < len(xs) and j < len(ys):
+        if xs[i] <= ys[j]:
+            result.append(xs[i])
+            i += 1
+        else:
+            result.append(ys[j])
+            j += 1
+
+    while i < len(xs):
+        result.append(xs[i])
+        i += 1
+
+    while j < len(ys):
+        result.append(ys[j])
+        j += 1
+
+    return result
+
+# A
+result = merge_sorted([3, 4, 6, 10, 11, 15], [1, 5, 8, 12, 14, 19])
+print(result)
+assert result == [1, 3, 4, 5, 6, 8, 10, 11, 12, 14, 15, 19]
+
+# B
+result = merge_sorted([], [1,2,3])
+print(result)
+assert result == [1,2,3]
+
+# C
+result = merge_sorted([1,2,3], [])
+print(result)
+assert result == [1,2,3]
+
+# D
+result = merge_sorted([], [])
+print(result)
+assert result == []
+
+# Wahoo!
+print("Success!")