Moved 1 to 5 to Python and learned a ton.

python/e004.py

@@ -0,0 +1,66 @@
+from lib_misc import is_palindrome
+
+
+def euler_004():
+    r = 0
+    for a in range(999, 99, -1):
+        for b in range(a, r // a, -1):
+            if is_palindrome(a * b) and a * b > r:
+                r = a * b
+    return r
+
+
+def euler_004_original():
+    """ The solution that I came up with originally. """
+    r = 0
+    for a in range(999, 99, -1):
+        if a * a < r:
+            break
+        for b in range(a, 99, -1):
+            c = a * b
+            if c > r and is_palindrome(c):
+                r = c
+    return r
+
+
+def euler_004_forum():
+    """
+    A solution from etatsui in the project Euler forum.
+    It is impressive to see how much fast it is relying on
+    mathematical tricks:
+        11(9091a + 910b + 100c) = mn;
+    Let:
+        11 * 10 < m < 11 * 90
+    """
+    for a in range(9, 0, -1):
+        for b in range(9, -1, -1):
+            for c in range(9, -1, -1):
+                num = 9091 * a + 910 * b + 100 * c
+                for m in range(90, 9, -1):
+                    if num % m == 0:
+                        if num / m > 999:
+                            break
+                        else:
+                            result = num * 11
+                            return result
+
+
+assert(euler_004() == 906609)
+print("e004.py: {}".format(euler_004()))
+
+
+def time_tests():
+    from timeit import timeit
+    assert(euler_004() == 906609)
+    assert(euler_004_original() == 906609)
+    assert(euler_004_forum() == 906609)
+
+    print(timeit(lambda: euler_004(), number=100))
+    print(timeit(lambda: euler_004_original(), number=100))
+    print(timeit(lambda: euler_004_forum(), number=100))
+
+
+# time_tests()
+# 0.5044660240000667
+# 0.7896412069985672
+# 0.04794573199978913