langs a-z

Task/Integer-sequence/CoffeeScript/integer-sequence-1.coffeescript

@@ -0,0 +1,35 @@
+# This very limited BCD-based collection of functions
+# makes it easy to count very large numbers.  All arrays
+# start off with the ones columns in position zero.
+# Using arrays of decimal-based digits to model integers
+# doesn't make much sense for most tasks, but if you
+# want to keep counting forever, this does the trick.
+
+BcdInteger =
+  from_string: (s) ->
+    arr = []
+    for c in s
+      arr.unshift parseInt(c)
+    arr
+
+  render: (arr) ->
+    s = ''
+    for elem in arr
+      s = elem.toString() + s
+    s
+
+  succ: (arr) ->
+    arr = (elem for elem in arr)
+    i = 0
+    while arr[i] == 9
+      arr[i] = 0
+      i += 1
+    arr[i] ||= 0
+    arr[i] += 1
+    arr
+
+# To start counting from 1, change the next line!
+big_int = BcdInteger.from_string "199999999999999999999999999999999999999999999999999999"
+while true
+  console.log BcdInteger.render big_int
+  big_int = BcdInteger.succ big_int