Add coding exercises for Facebook interviews

Add attempts at solving coding problems to Briefcase.

scratch/facebook/highest-product-of-3.py

@@ -0,0 +1,20 @@
+def hi_product(xs):
+    lowest_one, highest_one = min(xs[0], xs[1]), max(xs[0], xs[1])
+    lowest_two, highest_two = xs[0] * xs[1], xs[0] * xs[1]
+    highest = float('-inf')
+    for x in xs[2:]:
+        highest = max(highest, highest_two * x, lowest_two * x)
+        lowest_one = min(lowest_one, x)
+        highest_one = max(highest_one, x)
+        lowest_two = min(lowest_two, highest_one * x, lowest_one * x)
+        highest_two = max(highest_two, highest_one * x, lowest_one * x)
+    return highest
+
+xs = [([-10,-10,1,3,2], 300),
+      ([1,10,-5,1,-100], 5000)]
+
+for x, expected in xs:
+    result = hi_product(x)
+    print(x, result)
+    assert result == expected
+    print("Success!")