Solve 2017 day 14 to 17.

2017/d15.py

@@ -0,0 +1,59 @@
+from lib import str_to_int
+
+ 
+def part_1(data):
+    fa = 16807
+    fb = 48271
+    m = 2147483647
+
+    xs = []
+    for line in data.splitlines():
+        xs.append(str_to_int(line))
+    a, b = xs
+
+    c = 0
+    for _ in range(40_000_000):
+        a = (a * fa) % m
+        b = (b * fb) % m
+        if (a & 0xffff) == (b & 0xffff):
+            c += 1
+    print(c)
+
+
+def gen(a, f, m, d):
+    while True:
+        a = (a * f) % m
+        if a % d == 0:
+            yield a
+
+
+def part_2(data):
+    fa = 16807
+    fb = 48271
+    m = 2147483647
+
+    xs = []
+    for line in data.splitlines():
+        xs.append(str_to_int(line))
+    a, b = xs
+
+    xs = gen(a, fa, m, 4)
+    ys = gen(b, fb, m, 8)
+
+    c = 0
+    for _ in range(5_000_000):
+        a = next(xs)
+        b = next(ys)
+        if (a & 0xffff) == (b & 0xffff):
+            c += 1
+    print(c)
+
+
+def main():
+    data = open(0).read().strip()
+    part_1(data)
+    part_2(data)
+
+
+if __name__ == "__main__":
+    main()