new tasks

Task/Best_shuffle/Python/best_shuffle-2.py

@@ -0,0 +1,50 @@
+#!/usr/bin/env python
+
+def best_shuffle(s):
+    # Count the supply of characters.
+    from collections import defaultdict
+    count = defaultdict(int)
+    for c in s:
+        count[c] += 1
+
+    # Shuffle the characters.
+    r = []
+    for x in s:
+        # Find the best character to replace x.
+        best = None
+        rankb = -2
+        for c, rankc in count.items():
+            # Prefer characters with more supply.
+            # (Save characters with less supply.)
+            # Avoid identical characters.
+            if c == x: rankc = -1
+            if rankc > rankb:
+                best = c
+                rankb = rankc
+
+        # Add character to list. Remove it from supply.
+        r.append(best)
+        count[best] -= 1
+        if count[best] == 0: del count[best]
+
+    # If the final letter became stuck (as "ababcd" became "bacabd",
+    # and the final "d" became stuck), then fix it.
+    i = len(s) - 1
+    if r[i] == s[i]:
+        for j in range(i):
+            if r[i] != s[j] and r[j] != s[i]:
+                r[i], r[j] = r[j], r[i]
+                break
+
+    # Convert list to string. PEP 8, "Style Guide for Python Code",
+    # suggests that ''.join() is faster than + when concatenating
+    # many strings. See http://www.python.org/dev/peps/pep-0008/
+    r = ''.join(r)
+
+    score = sum(x == y for x, y in zip(r, s))
+
+    return (r, score)
+
+for s in "abracadabra", "seesaw", "elk", "grrrrrr", "up", "a":
+    shuffled, score = best_shuffle(s)
+    print("%s, %s, (%d)" % (s, shuffled, score))

Task/Best_shuffle/Python/best_shuffle.py

@@ -0,0 +1,28 @@
+from collections import Counter
+import random
+
+def count(w1,wnew):
+    return sum(c1==c2 for c1,c2 in zip(w1, wnew))
+
+def best_shuffle(w):
+    wnew = list(w)
+    n = len(w)
+    rangelists = (list(range(n)), list(range(n)))
+    for r in rangelists:
+        random.shuffle(r)
+    rangei, rangej = rangelists
+    for i in rangei:
+        for j in rangej:
+            if i != j and wnew[j] != wnew[i] and w[i] != wnew[j] and w[j] != wnew[i]:
+                wnew[j], wnew[i] = wnew[i], wnew[j]
+    wnew = ''.join(wnew)
+    return wnew, count(w, wnew)
+
+
+if __name__ == '__main__':
+    test_words = ('tree abracadabra seesaw elk grrrrrr up a '
+                  + 'antidisestablishmentarianism hounddogs').split()
+    test_words += ['aardvarks are ant eaters', 'immediately', 'abba']
+    for w in test_words:
+        wnew, c = best_shuffle(w)
+        print("%29s, %-29s ,(%i)" % (w, wnew, c))