Add days 7 and 8

day06.py

@@ -2,21 +2,25 @@ import fileinput
 from math import ceil, floor, sqrt
 
 def race(time, dist):
-    x1 = (time - sqrt(time * time - 4 * dist)) / 2
-    x2 = (time + sqrt(time * time - 4 * dist)) / 2
+    discr = sqrt(time * time - 4 * dist)
+    x1 = (time - discr) / 2
+    x2 = (time + discr) / 2
     x1, x2 = floor(x1) + 1, ceil(x2) - 1
     return x2 - x1 + 1
 
-input = list(fileinput.input())
-times = [int(x) for x in input[0][11:].split()]
-distances = [int(x) for x in input[1][11:].split()]
+def main():
+    input = list(fileinput.input())
+    times = [int(x) for x in input[0][11:].split()]
+    distances = [int(x) for x in input[1][11:].split()]
 
-part1 = 1
-for time, dist in zip(times, distances):
-    part1 *= race(time, dist)
+    part1 = 1
+    for time, dist in zip(times, distances):
+        part1 *= race(time, dist)
 
-time = int(input[0][11:].replace(" ", ""))
-dist = int(input[1][11:].replace(" ", ""))
-part2 = race(time, dist)
+    time = int(input[0][11:].replace(" ", ""))
+    dist = int(input[1][11:].replace(" ", ""))
+    part2 = race(time, dist)
 
-print(part1, part2)
+    print(part1, part2)
+
+main()

day07.py

@@ -0,0 +1,59 @@
+import fileinput
+from collections import Counter
+
+STRENGTHS = {
+    "A": 1,
+    "K": 2,
+    "Q": 3,
+    "T": 5,
+    "9": 6,
+    "8": 7,
+    "7": 8,
+    "6": 9,
+    "5": 10,
+    "4": 11,
+    "3": 12,
+    "2": 13,
+}
+
+INPUT = []
+for line in fileinput.input():
+    (hand, bid) = line.split()
+    counter = Counter(hand)
+    INPUT.append((hand, int(bid), counter["J"], counter.most_common() + [("", 0)]))
+
+def solve(part):
+    STRENGTHS["J"] = 14 if part == 2 else 4
+
+    hands = []
+    for (hand, bid, jokers, mcs) in INPUT:
+        if part == 2:
+            mcs = [(c, i) for (c, i) in mcs if c != "J"]
+        else:
+            jokers = 0
+        mc = mcs[0][1] + jokers
+
+        if mc == 5:
+            strength = 1
+        elif mc == 4:
+            strength = 2
+        elif mc == 3 and mcs[1][1] == 2:
+            strength = 3
+        elif mc == 3:
+            strength = 4
+        elif mc == 2 and mcs[1][1] == 2:
+            strength = 5
+        elif mc == 2:
+            strength = 6
+        else:
+            strength = 7
+
+        strengths = [STRENGTHS[c] for c in hand]
+        hands.append(([strength] + strengths, bid))
+
+    hands.sort(key=lambda h: h[0], reverse=True)
+    return sum((i + 1) * bid for (i, (_, bid)) in enumerate(hands))
+
+part1 = solve(part=1)
+part2 = solve(part=2)
+print(part1, part2)

day08.py

@@ -0,0 +1,34 @@
+import fileinput
+import math
+
+input = fileinput.input()
+
+instructions = next(input).strip()
+next(input)
+
+tree = {}
+
+for line in input:
+    if line.strip():
+        (parent, children) = line.split(" = ")
+        (left, right) = children[1:-2].split(", ")
+        tree[parent] = (left, right)
+
+nodes = [node for node in tree if node[2] == "A"]
+cycles = [0] * len(nodes)
+
+for i in range(len(nodes)):
+    while nodes[i][2] != "Z":
+        for instr in instructions:
+            cycles[i] += 1
+            if instr == "L":
+                (nodes[i], _) = tree[nodes[i]]
+            else:
+                (_, nodes[i]) = tree[nodes[i]]
+            if nodes[i][2] == "Z":
+                break
+
+part1 = cycles[nodes.index("ZZZ")]
+part2 = math.lcm(*cycles)
+
+print(part1, part2)