Add Python solution to challenge 055

2 files changed, 91 insertions, 0 deletions

diff --git a/challenge-055/paulo-custodio/python/ch-1.py b/challenge-055/paulo-custodio/python/ch-1.py
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+++ b/challenge-055/paulo-custodio/python/ch-1.py
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+#!/usr/bin/env python3
+
+# Challenge 055
+#
+# TASK #1
+# Flip Binary
+# You are given a binary number B, consisting of N binary digits 0 or 1: s0, s1,
+# …, s(N-1).
+#
+# Choose two indices L and R such that 0 = L = R < N and flip the digits s(L),
+# s(L+1), …, s(R). By flipping, we mean change 0 to 1 and vice-versa.
+#
+# For example, given the binary number 010, the possible flip pair results are
+# listed below:
+#
+# L=0, R=0 the result binary: 110
+# L=0, R=1 the result binary: 100
+# L=0, R=2 the result binary: 101
+# L=1, R=1 the result binary: 000
+# L=1, R=2 the result binary: 001
+# L=2, R=2 the result binary: 011
+# Write a script to find the indices (L,R) that results in a binary number with
+# maximum number of 1s. If you find more than one maximal pair L,R then print
+# all of them.
+#
+# Continuing our example, note that we had three pairs (L=0, R=0), (L=0, R=2),
+# and (L=2, R=2) that resulted in a binary number with two 1s, which was the
+# maximum. So we would print all three pairs.
+
+import sys
+
+bin = sys.argv[1]
+max_1s = 0
+max_1s_pairs = []
+
+for l in range(0, len(bin)-1+1):
+    for r in range(l, len(bin)-1+1):
+        bits = [int(x) for x in bin]
+        for i in range(l, r+1):
+            bits[i] = 1-bits[i]
+        _1s = len(list(filter(lambda x:x==1, bits)))
+        if _1s > max_1s:
+            max_1s = _1s
+            max_1s_pairs = [[l,r]]
+        elif _1s == max_1s:
+            max_1s_pairs.append([l,r])
+
+out = []
+for x in max_1s_pairs:
+    out.append("(L="+str(x[0])+", R="+str(x[1])+")")
+print(", ".join(out))
diff --git a/challenge-055/paulo-custodio/python/ch-2.py b/challenge-055/paulo-custodio/python/ch-2.py
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+++ b/challenge-055/paulo-custodio/python/ch-2.py
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+#!/usr/bin/env python3
+
+# Challenge 055
+#
+# TASK #2
+# 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.
+
+import sys
+
+def show_waves(wave, next):
+    if len(next) == 0:
+        print(" ".join([str(x) for x in wave]))
+    elif len(wave) == 0:
+        for i in range(len(next)):
+            show_waves(wave+[next[i]], next[:i]+next[i+1:])
+    elif len(wave) % 2 == 1:        # going down
+        for i in range(len(next)):
+            if wave[-1] >= next[i]:
+                show_waves(wave+[next[i]], next[:i]+next[i+1:])
+    else:                           # going up
+        for i in range(len(next)):
+            if wave[-1] <= next[i]:
+                show_waves(wave+[next[i]], next[:i]+next[i+1:])
+
+n = [int(x) for x in sys.argv[1:]]
+show_waves([], n)