First perfect square in base n with n unique digits: Difference between revisions

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 5            K99MDB35N8K25 -> ABDJNHCPF97GKMEI6OL8543201                402922566 05:15.307  06:49.008
 26           JJBO73E11F1101 -> A6N9QC7PKGFJIBHDMOLE8543201               457555291 06:01.338  12:50.347</pre>
+=={{header|Nim}}==
+{{trans|D}}
+<lang Nim>import algorithm, math, strformat
+const Alphabet = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+func toBaseN(num, base: Natural): string =
+  doAssert(base in 2..Alphabet.len, &"base must be in 2..{Alphabet.len}")
+  var num = num
+  while true:
+    result.add(Alphabet[num mod base])
+    num = num div base
+    if num == 0: break
+  result.reverse()
+func countUnique(str: string): int =
+  var charset: set['0'..'Z']
+  for ch in str: charset.incl(ch)
+  result = charset.card
+proc find(base: Natural) =
+  var n = pow(base.toFloat, (base - 1) / 2).int
+  while true:
+    let sq = n * n
+    let sqstr = sq.toBaseN(base)
+    if sqstr.len >= base and countUnique(sqstr) == base:
+      let nstr = n.toBaseN(base)
+      echo &"Base {base:2d}:  {nstr:>8s}² = {sqstr:<16s}"
+      break
+    inc n
+when isMainModule:
+  for base in 2..16:
+    base.find()</lang>
+{{out}}
+<pre>Base  2:        10² = 100
+Base  3:        22² = 2101
+Base  4:        33² = 3201
+Base  5:       243² = 132304
+Base  6:       523² = 452013
+Base  7:      1431² = 2450361
+Base  8:      3344² = 13675420
+Base  9:     11642² = 136802574
+Base 10:     32043² = 1026753849
+Base 11:    111453² = 1240A536789
+Base 12:    3966B9² = 124A7B538609
+Base 13:   3828943² = 10254773CA86B9
+Base 14:   3A9DB7C² = 10269B8C57D3A4
+Base 15:  1012B857² = 102597BACE836D4
+Base 16:  404A9D9B² = 1025648CFEA37BD9</pre>
 =={{header|Pascal}}==