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count-and-say.py
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count-and-say.py
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# https://leetcode.com/problems/count-and-say/
#
# The count-and-say sequence is the sequence of integers beginning as follows:
# 1, 11, 21, 1211, 111221, ...
#
# 1 is read off as "one 1" or 11.
# 11 is read off as "two 1s" or 21.
# 21 is read off as "one 2, then one 1" or 1211.
# Given an integer n, generate the nth sequence.
#
# Note: The sequence of integers will be represented as a string.
import unittest
class Solution(object):
def countAndSay(self, n):
"""
:type n: int
:rtype: str
"""
if n == 0:
return 0
seed = 1
if n == 1:
return "1"
else:
for i in xrange(n-1):
seed = self.do_seq(seed)
return seed
def do_seq(self,seed):
seed = str(seed)
if seed is None:
return None
elif len(seed)==1:
return str(1)+seed[0]
else:
count = 1
return_string = ""
for i in xrange(len(seed)-1):
if seed[i] == seed[i+1]:
count = count + 1
else:
return_string = return_string + str(count) + seed[i]
count = 1
return_string = return_string + str(count)+ seed[i+1]
return return_string
class TestCountAndSay(unittest.TestCase):
my_solution = Solution()
def test_n_equal_1(self):
self.assertEquals(self.my_solution.countAndSay(1),"1")
def test_n_equal_2(self):
self.assertEquals(self.my_solution.countAndSay(2),"11")
def test_n_equal_3(self):
self.assertEquals(self.my_solution.countAndSay(3),"21")
def test_n_equal_4(self):
self.assertEquals(self.my_solution.countAndSay(4),"1211")
def test_n_is_None(self):
self.assertEquals(self.my_solution.countAndSay(0),0)
if __name__ == "__main__":
unittest.main()