Bouncy numbers

112.py

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+import unittest
+
+def isIncreasing(n):
+	"""
+	Returns boolean whether number is increasing
+	Decreasing defined as whether next digit is larger or equal
+	"""
+	s = str(n)
+	b = True
+	for i in range(len(s) - 1):
+		if int(s[i]) > int(s[i + 1]):
+			b = False
+	return b
+
+def isDecreasing(n):
+	"""
+	Returns boolean whether number is decreasing
+	Decreasing defined as whether next digit is smaller or equal
+	"""
+	s = str(n)
+	b = True
+	for i in range(len(s) - 1):
+		if int(s[i]) < int(s[i + 1]):
+			b = False
+	return b
+
+def isBouncy(n):
+	"""
+	Returns boolean whether number is bouncy
+	Bouncy defined as not increasing or decreasing
+	"""
+	return not (isIncreasing(n) or isDecreasing(n))
+
+def main(n):
+	bouncy = 0.0            # Number of bouncy numbers so far
+	total = 0               # Also functions as a counter
+	prop = 0.0              # Proportion of bouncy numbers
+
+	while prop < n:
+		total += 1
+		if isBouncy(total):
+			bouncy += 1
+		prop = bouncy / total
+
+	return total
+
+# Testing suite
+# Based on Project Euler description
+class Bouncy(unittest.TestCase):
+	def test_increasing(self):
+		self.assertTrue(isIncreasing(134468))
+		self.assertFalse(isIncreasing(66420))
+		self.assertFalse(isIncreasing(155349))
+	def test_decreasing(self):
+		self.assertFalse(isDecreasing(134468))
+		self.assertTrue(isDecreasing(66420))
+		self.assertFalse(isDecreasing(155349))
+	def test_bouncy(self):
+		self.assertFalse(isBouncy(134468))
+		self.assertFalse(isBouncy(66420))
+		self.assertTrue(isBouncy(155349))
+
+	def test_50bouncy(self):
+		self.assertEqual(538, main(0.5))
+
+	def test_90bouncy(self):
+		self.assertEqual(21780, main(0.9))
+
+if __name__ == "__main__":
+	print main(0.99)
+	unittest.main()