Add Python solution to challenge 149

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diff --git a/challenge-149/paulo-custodio/python/ch-2.py b/challenge-149/paulo-custodio/python/ch-2.py
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+#!/usr/bin/env python3
+
+# Challenge 149
+#
+# TASK #2 > Largest Square
+# Submitted by: Roger Bell_West
+# Given a number base, derive the largest perfect square with no repeated
+# digits and return it as a string. (For base>10, use 'A'..'Z'.)
+#
+# Example:
+#     f(2)="1"
+#     f(4)="3201"
+#     f(10)="9814072356"
+#     f(12)="B8750A649321"
+
+import sys
+import math
+from itertools import permutations
+
+def largest_perfect_square(base):
+    digits = [str(i) for i in range(10)] + [chr(i) for i in range(ord('A'), ord('A') + 26)]
+    digits = digits[:base]
+
+    max_num = 0
+    max_str = "0"
+
+    for permu in permutations(digits, base):
+        str_num = ''.join(permu)
+        str_num = str_num.lstrip('0') or '0'
+        num = int(str_num, base)
+
+        if math.isqrt(num) ** 2 == num:  # is perfect square
+            if num > max_num:
+                max_num, max_str = num, str_num
+
+    return max_str
+
+base = int(sys.argv[1])
+print(largest_perfect_square(base))