Display the names of numbers

python/number-words.py

@@ -0,0 +1,65 @@
+import collections
+import sys
+
+DIGITS = {
+  "1": ["one", "ten", "eleven"],
+  "2": ["two", "twenty", "twelve"],
+  "3": ["three", "thirty", "thirteen"],
+  "4": ["four", "forty", "fourteen"],
+  "5": ["five", "fifty", "fifteen"],
+  "6": ["six", "sixty", "sixteen"],
+  "7": ["seven", "seventy", "seventeen"],
+  "8": ["eight", "eighty", "eighteen"],
+  "9": ["nine", "ninety", "nineteen"]
+}
+
+PLACES = [
+  "", "thousand", "million", "billion", "trillion"
+]
+
+number = "42"
+
+if len(sys.argv) > 1:
+  number = sys.argv[1]
+
+idx = len(number)
+groups = []
+
+while idx > 0:
+  start = idx - 3
+
+  if start < 0:
+    start = 0
+
+  groups.append(number[start:idx])
+  idx = start
+
+word = collections.deque([])
+idx = 0
+
+for group in groups:
+  special = False
+  combined = []
+
+  if len(group) == 3 and group[0] != "0":
+    combined.append(DIGITS[group[0]][0] + " hundred")
+
+  if len(group) > 1:
+    if group[-2] == "1" and group[-1] != "0":
+      combined.append(DIGITS[group[-1]][2])
+      special = True
+    elif group[-2] in DIGITS:
+      combined.append(DIGITS[group[-2]][1])
+
+  if not special and group[-1] in DIGITS:
+    combined.append(DIGITS[group[-1]][0])
+
+  if group != "000":
+    combined.append(PLACES[idx])
+
+  if len(combined) > 0:
+    word.appendleft(" ".join(combined))
+
+  idx += 1
+
+print(" ".join(word).rstrip())