A-M baby

Task/Long-multiplication/Python/long-multiplication-1.py

@@ -0,0 +1,2 @@
+#!/usr/bin/env python
+print 2**64*2**64

Task/Long-multiplication/Python/long-multiplication-2.py

@@ -0,0 +1,33 @@
+#!/usr/bin/env python
+
+def add_with_carry(result, addend, addendpos):
+    while True:
+        while len(result) < addendpos + 1:
+            result.append(0)
+        addend_result = str(int(addend) + int(result[addendpos]))
+        addend_digits = list(addend_result)
+        result[addendpos] = addend_digits.pop()
+
+        if not addend_digits:
+            break
+        addend = addend_digits.pop()
+        addendpos += 1
+
+def longhand_multiplication(multiplicand, multiplier):
+    result = []
+    for multiplicand_offset, multiplicand_digit in enumerate(reversed(multiplicand)):
+        for multiplier_offset, multiplier_digit in enumerate(reversed(multiplier), start=multiplicand_offset):
+            multiplication_result = str(int(multiplicand_digit) * int(multiplier_digit))
+
+            for addend_offset, result_digit_addend in enumerate(reversed(multiplication_result), start=multiplier_offset):
+                add_with_carry(result, result_digit_addend, addend_offset)
+
+    result.reverse()
+
+    return ''.join(result)
+
+if __name__ == "__main__":
+    sixtyfour = "18446744073709551616"
+
+    onetwentyeight = longhand_multiplication(sixtyfour, sixtyfour)
+    print(onetwentyeight)

Task/Long-multiplication/Python/long-multiplication-3.py

@@ -0,0 +1,20 @@
+#!/usr/bin/env python
+
+def digits(x):
+    return [int(c) for c in str(x)]
+
+def mult_table(xs, ys):
+    return [[x * y for x in xs] for y in ys]
+
+def polymul(xs, ys):
+    return map(lambda *vs: sum(filter(None, vs)),
+               *[[0] * i + zs for i, zs in enumerate(mult_table(xs, ys))])
+
+def longmult(x, y):
+    result = 0
+    for v in polymul(digits(x), digits(y)):
+        result = result * 10 + v
+    return result
+
+if __name__ == "__main__":
+    print longmult(2**64, 2**64)