Solution to problem 17

src/Python/Problem017.py

@@ -0,0 +1,62 @@
+#!/usr/bin/env python3
+"""
+Created on 13 Jan 2018
+
+@author: David Doblas Jiménez
+@email: daviddoji@pm.me
+
+Solution for problem 17 of Project Euler
+https://projecteuler.net/problem=17
+"""
+
+from utils import timeit
+
+def num2letters(num):
+    nums = {0: '', 1: 'one', 2: 'two', 3: 'three', 4: 'four', 5: 'five',
+            6: 'six', 7: 'seven', 8: 'eight', 9: 'nine', 10: 'ten',
+            11: 'eleven', 12: 'twelve', 13: 'thirteen', 14: 'fourteen',
+            15: 'fifteen', 16: 'sixteen', 17: 'seventeen', 18: 'eighteen',
+            19: 'nineteen', 20: 'twenty', 30: 'thirty', 40: 'forty',
+            50: 'fifty', 60: 'sixty', 70: 'seventy', 80: 'eighty',
+            90: 'ninety', 100: 'hundred', 1000: 'thousand'}
+
+    if num <= 20:
+        return len(nums[num])
+    elif num < 100:
+        tens, units = divmod(num, 10)
+        return len(nums[tens * 10]) + num2letters(units)
+    elif num < 1000:
+        hundreds, rest = divmod(num, 100)
+        if rest:
+            return num2letters(hundreds) + len(nums[100]) + len('and') +\
+                   num2letters(rest)
+        else:
+            return num2letters(hundreds) + len(nums[100])
+    else:
+        thousands, rest = divmod(num, 1000)
+        return num2letters(thousands) + len(nums[1000])
+
+@timeit("Problem 17")
+def compute():
+    """
+    If the numbers 1 to 5 are written out in words: one, two, three, four,
+    five, then there are 3 + 3 + 5 + 4 + 4 = 19 letters used in total.
+
+    If all the numbers from 1 to 1000 (one thousand) inclusive were written
+    out in words, how many letters would be used?
+
+    NOTE: Do not count spaces or hyphens. For example, 342 (three hundred and
+    forty-two) contains 23 letters and 115 (one hundred and fifteen) contains
+    20 letters. The use of "and" when writing out numbers is in compliance
+    with British usage.
+    """
+    n = 1000
+    letters = 0
+    for num in range(1, n + 1):
+        letters += num2letters(num)
+    return letters
+
+
+if __name__ == "__main__":
+
+    print(f"Result for Problem 17: {compute()}")