Add InterviewCake.com examples

Adds some of the code I generated while studying for a role transfer at Google
using the fantastic resource, InterviewCake.com. This work predates the
mono-repo.

I should think of ways to DRY up this code and the code in
crack_the_coding_interview, but I'm afraid I'm creating unnecessary work for
myself that way.

data_structures_and_algorithms/temperature-tracker.py

@@ -0,0 +1,84 @@
+import unittest
+
+
+################################################################################
+# Solution
+################################################################################
+class TempTracker(object):
+    def __init__(self):
+        # min / max
+        self.min = None
+        self.max = None
+        # mean
+        self.sum = 0
+        self.num = 0
+        # mode
+        self.nums = [0] * 111
+        self.mode_num = 0
+        self.mode = None
+
+    def insert(self, x):
+        # min / max
+        if not self.min or x < self.min:
+            self.min = x
+        if not self.max or x > self.max:
+            self.max = x
+        # mean
+        self.sum += x
+        self.num += 1
+        # mode
+        self.nums[x] += 1
+        if self.nums[x] >= self.mode_num:
+            self.mode_num = self.nums[x]
+            self.mode = x
+
+    def get_max(self):
+        return self.max
+
+    def get_min(self):
+        return self.min
+
+    def get_mean(self):
+        return self.sum / self.num
+
+    def get_mode(self):
+        return self.mode
+
+
+# Tests
+
+
+class Test(unittest.TestCase):
+    def test_tracker_usage(self):
+        tracker = TempTracker()
+
+        tracker.insert(50)
+        msg = 'failed on first temp recorded'
+        self.assertEqual(tracker.get_max(), 50, msg='max ' + msg)
+        self.assertEqual(tracker.get_min(), 50, msg='min ' + msg)
+        self.assertEqual(tracker.get_mean(), 50.0, msg='mean ' + msg)
+        self.assertEqual(tracker.get_mode(), 50, msg='mode ' + msg)
+
+        tracker.insert(80)
+        msg = 'failed on higher temp recorded'
+        self.assertEqual(tracker.get_max(), 80, msg='max ' + msg)
+        self.assertEqual(tracker.get_min(), 50, msg='min ' + msg)
+        self.assertEqual(tracker.get_mean(), 65.0, msg='mean ' + msg)
+        self.assertIn(tracker.get_mode(), [50, 80], msg='mode ' + msg)
+
+        tracker.insert(80)
+        msg = 'failed on third temp recorded'
+        self.assertEqual(tracker.get_max(), 80, msg='max ' + msg)
+        self.assertEqual(tracker.get_min(), 50, msg='min ' + msg)
+        self.assertEqual(tracker.get_mean(), 70.0, msg='mean ' + msg)
+        self.assertEqual(tracker.get_mode(), 80, msg='mode ' + msg)
+
+        tracker.insert(30)
+        msg = 'failed on lower temp recorded'
+        self.assertEqual(tracker.get_max(), 80, msg='max ' + msg)
+        self.assertEqual(tracker.get_min(), 30, msg='min ' + msg)
+        self.assertEqual(tracker.get_mean(), 60.0, msg='mean ' + msg)
+        self.assertEqual(tracker.get_mode(), 80, msg='mode ' + msg)
+
+
+unittest.main(verbosity=2)