Solve 2017 day 14 to 17.

2017/d14.py

@@ -0,0 +1,72 @@
+from lib import Grid2D
+from d10 import part_2 as hash
+
+
+def to_bin(x):
+    assert len(x) == 1
+    xv = int(x, 16)
+    c = 1
+    r = ""
+    for _ in range(4):
+        if c & xv > 0:
+            r = "1" + r
+        else:
+            r = "0" + r
+        c = (c << 1)
+    return r
+
+def to_bits(xs):
+    r = ""
+    for x in xs:
+        r += to_bin(x)
+    return r
+
+def part_1(data):
+    r = 0
+    for i in range(128):
+        s = f"{data}-{i}"
+        x = hash(s)
+        b = to_bits(x)
+        r += b.count("1")
+    print(r)
+
+
+def part_2(data):
+    grid = ""
+    for i in range(128):
+        s = f"{data}-{i}"
+        x = hash(s)
+        grid += to_bits(x)
+        grid += "\n"
+
+    g = Grid2D(grid)
+
+    one_group_count = 0
+    seen_ones = set()
+    all_ones = g.find("1")
+    for c in all_ones:
+        if c in seen_ones:
+            continue
+        one_group_count += 1
+
+        current_group = [c]
+        while current_group:
+            c = current_group.pop()
+            if c in seen_ones:
+                continue
+            seen_ones.add(c)
+
+            for nb in g.neighbors_ort(c):
+                if g[nb] == "1":
+                    current_group.append(nb)
+    print(one_group_count)
+
+
+def main():
+    data = open(0).read().strip()
+    part_1(data)
+    part_2(data)
+
+
+if __name__ == "__main__":
+    main()

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()

2017/d16.py

@@ -0,0 +1,60 @@
+from lib import LETTERS_LOWER, str_to_int, str_to_ints
+ 
+
+def one_cycle(xs, insts):
+    for inst in insts:
+        if inst.startswith("s"):
+            v = str_to_int(inst)
+            if v != 0:
+                xs = xs[-v:] + xs[:len(xs) - v]
+        elif inst.startswith("x"):
+            a, b = str_to_ints(inst)
+            xs[a], xs[b] = xs[b], xs[a]
+        elif inst.startswith("p"):
+            la, lb = inst[1], inst[3]
+            a, b = xs.index(la), xs.index(lb)
+            xs[a], xs[b] = xs[b], xs[a]
+        else:
+            assert False
+    return xs
+
+
+def part_1(data):
+    xs = list(LETTERS_LOWER[:16])
+    insts = data.split(",")
+    xs = one_cycle(xs, insts)
+    r = "".join(xs)
+    print(r)
+
+
+def part_2(data):
+    repeat = 10**9
+    xs = list(LETTERS_LOWER[:16])
+    insts = data.split(",")
+    cycle = 0
+    seen = {}
+    for i in range(repeat):
+        xs = one_cycle(xs, insts)
+        xst = tuple(xs)
+        if not xst in seen:
+            seen[xst] = i
+        else:
+            cycle = (i - seen[xst])
+            break
+
+    xs = list(LETTERS_LOWER[:16])
+    repeat %= cycle
+    for i in range(repeat):
+        xs = one_cycle(xs, insts)
+    r = "".join(xs)
+    print(r)
+
+
+def main():
+    data = open(0).read().strip()
+    part_1(data)
+    part_2(data)
+
+
+if __name__ == "__main__":
+    main()

2017/d17.py

@@ -0,0 +1,39 @@
+def part_1(data):
+    target = 2017
+    steps = int(data)
+    xs = [0]
+    i = 0
+    for n in range(1, target + 1):
+        i = (i + steps) % len(xs)
+        xs.insert(i + 1, n)
+        i += 1
+
+    for j in range(len(xs)):
+        if xs[j] == target:
+            print(xs[j + 1])
+            return
+
+
+def part_2(data, m=50_000_000):
+    steps = int(data)
+    len_xs = 1
+    last_zero = None
+    i = 0
+    for n in range(1, m + 1):
+        i = (i + steps) % len_xs
+        if i == 0:
+            last_zero = n
+        len_xs += 1
+        i += 1
+    return last_zero
+
+def main():
+    data = open(0).read().strip()
+    part_1(data)
+    assert part_2(data, 1000) == 531
+    assert part_2(data, 10000) == 2616
+    print(part_2(data))
+
+
+if __name__ == "__main__":
+    main()

README.md

@@ -74,4 +74,7 @@ written in Python.
 - Day 11: 66:06
 - Day 12: 6:44
 - Day 13: 120:00
-- Day 14:
+- Day 14: 17:48
+- Day 15: 11:40
+- Day 16: 13:16
+- Day 17: