Data commit

Task/Best-shuffle/Lua/best-shuffle.lua

@@ -0,0 +1,41 @@
+math.randomseed(os.time())
+
+local function shuffle(t)
+  for i = #t, 2, -1 do
+    local j = math.random(i)
+    t[i], t[j] = t[j], t[i]
+  end
+end
+
+local function bestshuffle(s, r)
+  local order, shufl, count = {}, {}, 0
+  for ch in s:gmatch(".") do order[#order+1], shufl[#shufl+1] = ch, ch end
+  if r then shuffle(shufl) end
+  for i = 1, #shufl do
+    for j = 1, #shufl do
+      if i ~= j and shufl[i] ~= order[j] and shufl[j] ~= order[i] then
+        shufl[i], shufl[j] = shufl[j], shufl[i]
+      end
+    end
+  end
+  for i = 1, #shufl do
+    if shufl[i] == order[i] then
+      count = count + 1
+    end
+  end
+  return table.concat(shufl), count
+end
+
+local words = { "abracadabra", "seesaw", "elk", "grrrrrr", "up", "a" }
+
+local function test(r)
+  print(r and "RANDOM:" or "DETERMINISTIC:")
+  for _, word in ipairs(words) do
+    local shufl, count = bestshuffle(word, r)
+    print(string.format("%s, %s, (%d)", word, shufl, count))
+  end
+  print()
+end
+
+test(true)
+test(false)