.

CS1032/lecture-2023-11-23/crypt.py

@@ -0,0 +1,17 @@
+from hashlib import sha256
+from itertools import cycle
+import base64
+
+def crypt(msg: bytes, key: str) -> bytes:
+	key_h = sha256()
+	key_h.update(key.encode('utf8'))
+	key = key_h.digest()
+
+	return bytes(p ^ k for (p, k) in zip(msg, cycle(key)))
+
+def encrypt(msg: str, key: str) -> str:
+	return base64.b64encode(crypt(bytes(msg, 'utf8'), key)).decode('utf8')
+
+def decrypt(msg: str, key: str) -> str:
+	return crypt(base64.b64decode(msg), key).decode('utf8')
+

CS1032/lecture-2023-11-23/nqueens.pl

@@ -0,0 +1,19 @@
+safe(Q1X-Q1Y, Q2X-Q2Y) :-
+	between(0, 7, Q1Y),
+	between(0, 7, Q2Y),
+	Q1X =\= Q2X,
+	Q1Y =\= Q2Y,
+	abs(Q1X - Q2X) =\= abs(Q1Y - Q2Y).
+safe(_, []).
+safe(QN, [Q | QS]) :- safe(QN, [Q | QS], 1).
+safe(_, [], _).
+safe(QN, [Q | QS], QX) :- safe(0-QN, QX-Q), safe(QN, QS, QX + 1).
+
+add(Qs, QsN) :-
+	QsN = [Q | Qs],
+	safe(Q, Qs).
+
+add(1, Qs, QsN) :- add(Qs, QsN).
+add(N, Qs, QsN) :- add(Qs, QA), add(M, QA, QsN), succ(M, N).
+
+solution(Qs) :- add(8, [], Qs).

CS1032/lecture-2023-11-23/nqueens.py

@@ -0,0 +1,18 @@
+def safe(q1, q2):
+    (q1x, q1y) = q1
+    (q2x, q2y) = q2
+    return q1x != q2x and q1y != q2y and abs(q1x - q2x) != abs(q1y - q2y)
+
+def possible_positions(current, n):
+    return ((*current, y) for y in range(n) if all(safe((len(current), y), q) for q in enumerate(current)))
+
+def solutions_r(current, n = 8):
+    if len(current) == n:
+        yield current
+        return
+
+    for pos in possible_positions(current, n):
+        yield from solutions_r(pos, n)
+
+def solutions(n = 8):
+    return solutions_r((), n)

CS1032/lecture-2023-11-23/pat.py

@@ -0,0 +1,7 @@
+def l(n=9):
+    for x in range(1, n):
+        print(" " * (x % 2), "*")
+
+def r(n=5):
+    for x in range(n, -1, -1):
+        print("*" * (x * 2 + 1))