Simon's solution to challenge 216

2 files changed, 93 insertions, 0 deletions

diff --git a/challenge-216/sgreen/python/ch-1.py b/challenge-216/sgreen/python/ch-1.py
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+++ b/challenge-216/sgreen/python/ch-1.py
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+#!/usr/bin/env python3
+
+import sys
+
+
+def get_frequency(word):
+    '''Return a dict with the frequency of each letter'''
+    freq = {}
+    for letter in word.upper():
+        if 'A' <= letter <= 'Z':
+            freq[letter] = freq.get(letter, 0) + 1
+
+    return freq
+
+
+def main(words):
+    # The last value is the plate we are matching
+    plate = words.pop()
+    plate_freq = get_frequency(plate)
+    solution = []
+
+    for word in words:
+        # Calculate the frequency of letters in the current word
+        word_freq = get_frequency(word)
+        for letter, cnt in plate_freq.items():
+            # Check that letters in the plate appear in the word
+            if letter not in word_freq or cnt > word_freq[letter]:
+                break
+        else:
+            solution.append(word)
+
+    print(*solution, sep=', ')
+
+
+if __name__ == '__main__':
+    main(sys.argv[1:])
diff --git a/challenge-216/sgreen/python/ch-2.py b/challenge-216/sgreen/python/ch-2.py
new file mode 100755
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+++ b/challenge-216/sgreen/python/ch-2.py
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+#!/usr/bin/env python3
+
+import itertools
+import math
+import sys
+
+
+def get_frequency(word):
+    freq = {}
+    for letter in word:
+        if 'a' <= letter <= 'z':
+            freq[letter] = freq.get(letter, 0) + 1
+
+    return freq
+
+
+def main(words):
+    # The last value is the word we are matching
+    target_word = words.pop()
+    target_freq = get_frequency(target_word)
+
+    # Lets check that a solution is possible
+    combined = ''.join(words)
+    for letter in target_freq:
+        if letter not in combined:
+            # The letter doesn't exist in the words, so no solution is possible
+            print(0)
+            return
+
+    # What is the highest frequency
+    highest = max(target_freq.values())
+    word_count = len(words)
+    min_stickers = math.inf
+
+    for freq in itertools.product(range(highest+1), repeat=word_count):
+        if sum(freq) >= min_stickers:
+            # This solution won't be better, so skip it
+            continue
+
+        # Combine all the words with the defined frequency
+        sticker_letters = ''.join([words[x] * freq[x]
+                                  for x in range(word_count)])
+        sticker_freq = get_frequency(sticker_letters)
+
+        for letter in target_freq:
+            if letter not in sticker_freq or sticker_freq[letter] < target_freq[letter]:
+                # Either a letter is missing, or doesn't occur enough times
+                break
+        else:
+            # We have a new solution with fewer letters
+            min_stickers = sum(freq)
+
+    print(min_stickers)
+
+
+if __name__ == '__main__':
+    main(sys.argv[1:])