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Task/Happy-numbers/Nim/happy-numbers.nim

@@ -0,0 +1,20 @@
+import intsets
+
+proc happy(n: int): bool =
+  var
+    n = n
+    past = initIntSet()
+  while n != 1:
+    let s = $n
+    n = 0
+    for c in s:
+      let i = ord(c) - ord('0')
+      n += i * i
+    if n in past:
+      return false
+    past.incl(n)
+  return true
+
+for x in 0..31:
+  if happy(x):
+    echo x