Best shuffle: Difference between revisions

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 =={{header|Python}}==
+===Swap if it is locally better algorithm===
+<lang python>from collections import Counter
+def count(w1,w2):
+    return sum(c1==c2 for c1,c2 in zip(w1, w2))
+def best_shuffle(w):
+    w2, w2old = list(w), []
+    n = len(w)
+    rangew = range(n)
+    while w2old != w2 and n:
+        n -= 1
+        w2old = w2[:]
+        for i in rangew:
+            for j in rangew:
+                if i != j and w2[j] != w2[i] and w[i] != w2[j] and w[j] != w2[i]:
+                    w2[j], w2[i] = w2[i], w2[j]
+    w2 = ''.join(w2)
+    return w2, count(w, w2)
+if __name__ == '__main__':
+    test_words = 'tree abracadabra seesaw, elk grrrrrr up a'.split()
+    for w in 'tree abracadabra seesaw elk grrrrrr up a'.split():
+        print(w, '->', best_shuffle(w))</lang>
+;Sample output
+<pre>tree -> ('eert', 0)
+abracadabra -> ('baadrbaraac', 0)
+seesaw -> ('eswaes', 0)
+elk -> ('kel', 0)
+grrrrrr -> ('rgrrrrr', 5)
+up -> ('pu', 0)
+a -> ('a', 1)</pre>
+===Alternative algorithm #1===
 {{needs-review|Python|This example uses a different algorithm, which is not like the other examples. This algorithm can become stuck near the end of the string. The code now fixes the problem if a "final letter became stuck", but this might or might not fix all inputs.}}