Finished existing ipython solutions to python. Ready to continue in pure python.

python/e061.py

@@ -1,8 +1,59 @@
+def get_four_digit_numbers(function):
+    r = []
+    n = 1
+    f = function
+    while f(n) < 10000:
+        if f(n) > 999:
+            r.append(f(n))
+        n += 1
+    return r
+
+
+def search_solution(aggregator, polygonals):
+    if not polygonals:
+        if is_cyclic(aggregator[-1], aggregator[0]):
+            return aggregator
+        else:
+            return []
+
+    if not aggregator:
+        for polygonal in polygonals:
+            for number in polygonal:
+                aggregator.append(number)
+                s = search_solution(
+                    aggregator, [p for p in polygonals if p != polygonal])
+                if s:
+                    return s
+                aggregator.pop()
+
+    for polygonal in polygonals:
+        for number in polygonal:
+            if is_cyclic(aggregator[-1], number) and number not in aggregator:
+                aggregator.append(number)
+                s = search_solution(
+                    aggregator, [p for p in polygonals if p != polygonal])
+                if s:
+                    return s
+                aggregator.pop()
+    return []
+
+
+def is_cyclic(a, b):
+    return str(a)[-2:] == str(b)[:2]
+
 
 def euler_061():
-    return 0
+    triangles = get_four_digit_numbers(lambda n: n * (n + 1) // 2)
+    squares = get_four_digit_numbers(lambda n: n**2)
+    pentas = get_four_digit_numbers(lambda n: n * (3 * n - 1) // 2)
+    hexas = get_four_digit_numbers(lambda n: n * (2 * n - 1))
+    heptas = get_four_digit_numbers(lambda n: n * (5 * n - 3) // 2)
+    octas = get_four_digit_numbers(lambda n: n * (3 * n - 2))
+    s = search_solution([], [triangles, squares, pentas, hexas, heptas, octas])
+    s = sum(s)
+    return s
 
 
 if __name__ == "__main__":
     print("e061.py: " + str(euler_061()))
-    assert(euler_061() == 0)
+    assert(euler_061() == 28684)