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#!/usr/bin/env python
# Challenge 097
#
# TASK #2 › Binary Substings
# Submitted by: Mohammad S Anwar
# You are given a binary string $B and an integer $S.
#
# Write a script to split the binary string $B of size $S and then find the
# minimum number of flips required to make it all the same.
#
# Example 1:
# Input: $B = “101100101”, $S = 3
# Output: 1
#
# Binary Substrings:
# "101": 0 flip
# "100": 1 flip to make it "101"
# "101": 0 flip
# Example 2:
# Input $B = “10110111”, $S = 4
# Output: 2
#
# Binary Substrings:
# "1011": 0 flip
# "0111": 2 flips to make it "1011"
import sys
import re
def bit_flips(bitstring, n):
def str_flips(a, b):
a = [c for c in a]
b = [c for c in b]
flips = 0;
for i in range(0, len(a)):
if a[i] != b[i]:
flips += 1
return flips
bits = [bitstring[i:i+n] for i in range(0, len(bitstring), n)]
flips = 0
for i in range(1, len(bits)):
flips += str_flips(bits[0], bits[i])
return flips
# main
assert len(sys.argv) == 3, "Usage: ch-2.py BITS N"
assert re.match(r"^[01]+$", sys.argv[1]), "BITS must be a bit string"
assert re.match(r"^\d+$", sys.argv[2]), "N must be a number"
assert len(sys.argv[1]) % int(sys.argv[2]) == 0, "N must be multiple of size of BITS"
bits, n = sys.argv[1], int(sys.argv[2])
print(bit_flips(bits,n))
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