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#!/usr/bin/env python3
###########################################################################
# script name: ch-2.py #
# #
# https://github.com/user-person #
# #
# https://perlweeklychallenge.org/blog/perl-weekly-challenge-055/ #
# #
# Wave Array #
# Any array N of non-unique, unsorted integers can be arranged into a #
# wave-like array such that n1 => n2 <= n3 => n4 <= n5 and so on. #
# For example, given the array [1, 2, 3, 4], possible wave arrays #
# include [2, 1, 4, 3] or [4, 1, 3, 2], since 2 => 1 <= 4 => 3 <= #
# and 4 => 1 <= 3 => 2. This is not a complete list. #
# Write a script to print all possible wave arrays for an integer array #
# N of arbitrary length. #
# #
# Notes: #
# When considering N of any length, note that the first element is #
# always greater than or equal to the second, and then the <= => <= #
# sequence alternates until the end of the array. #
# #
###########################################################################
from itertools import permutations
import re
import sys
n = [ 1, 2, 3, 4]
if len(sys.argv) > 1:
argString = ' '.join(sys.argv[1:])
matchObj = re.match(r'\A\s*([[(\{<])\s*', argString)
if matchObj:
pair = { '[' : ']', '(' : ')', '{' : '}', '<' : '>'}
pairMatch = pair[ matchObj.group(0) ]
argString = re.sub(r'\A\s*[[(\{<]\s*','',argString)
argString = re.sub('\s*'+re.escape(pairMatch)+'\s*\Z', '', argString)
argString = re.sub(r'\s*,\s*',' ',argString)
n = [int(x) for x in argString.split(" ")]
else:
sys.stderr.write('No arguments given. Using example data: [1, 2, 3, 4]\n')
for num in n:
if type(num) != int:
sys.stderr.write('Non-numeric input detected.\n')
sys.exit(1)
for set in permutations(n):
i = 0
for i in range(len(set)):
if i == 0:
continue
if i % 2 == 0: # EVEN
if set[i-1] > set[i]:
break
else: # ODD
if set[i-1] < set[i]:
break
else:
for x in set:
print(x,end=' ')
else:
print()
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