Solve 2015 days 11-18.

2015/d15.py

@@ -0,0 +1,34 @@
+import lib
+data = open(0).read().strip()
+
+part_1 = True
+def maximize(tspr, score, ks):
+    if ks == [] or tspr == 0:
+        r = 1
+        for s in score[:-1]:
+            if s < 0:
+                return 0
+            r *= s
+        if part_1:
+            return r
+        elif score[-1] == 500:
+            return r
+        else:
+            return 0
+    
+    m = 0
+    for tsp in range(tspr + 1):
+        dscore = [v * tsp  for v in ks[0]]
+        nscore = list(map(sum, zip(score, dscore)))
+        nm = maximize(tspr - tsp, nscore, ks[1:])
+        m = max(m, nm)
+    return m
+
+ks = []
+for line in data.splitlines():
+    k = lib.str_to_ints(line)
+    ks.append(k)
+
+score = [0 for _ in range(len(ks[0]))]
+print(maximize(100, score, ks))
+

2015/d16.py

@@ -0,0 +1,48 @@
+import re
+data = open(0).read().strip()
+
+target = {
+    "children": 3,
+    "cats": 7,
+    "samoyeds": 2,
+    "pomeranians": 3,
+    "akitas": 0,
+    "vizslas": 0,
+    "goldfish": 5,
+    "trees": 3,
+    "cars": 2,
+    "perfumes": 1,
+}
+
+part_1 = False
+for i, line in enumerate(data.splitlines()):
+    _, r = re.split(r"\d+: ", line)
+    d = {"index": i + 1}
+    kvs = r.split(", ")
+    for kv in kvs:
+        key, val = kv.split(": ")
+        val = int(val)
+        d[key] = val
+
+    if part_1:
+        for k, v in d.items():
+            if k in target and target[k] != v:
+                break
+        else:
+            print(d['index'])
+    else:
+        for k, v in d.items():
+            if k in target and (k == "cats" or k == "trees"):
+                if v > target[k]:
+                    continue
+                else:
+                    break
+            elif k in target and (k == "pomeranians" or k == "goldfish"):
+                if v < target[k]:
+                    continue
+                else:
+                    break
+            elif k in target and target[k] != v:
+                break
+        else:
+            print(d['index'])

2015/d17.py

@@ -0,0 +1,26 @@
+from itertools import combinations
+data = open(0).read().strip()
+
+cons = list(map(int, data.splitlines()))
+part_1 = False
+if part_1:
+    def count(n, cons):
+        if n == 0:
+            return 1
+        elif len(cons) == 0:
+            return 0
+        r = 0
+        first = cons[0]
+        r += count(n - first, cons[1:])
+        r += count(n, cons[1:])
+        return r
+    print(count(150, cons))
+else:
+    r = 0
+    for i in range(1, len(cons) + 1):
+        for c in combinations(cons, i):
+            if sum(c) == 150:
+                r += 1
+        if r > 0:
+            print(i)
+            break

2015/d18.py

@@ -0,0 +1,40 @@
+data = open(0).read().strip()
+
+part_2 = False
+rows = list(map(str, data.splitlines()))
+nrows = len(rows)
+ncols = len(rows[0])
+
+for _ in range(100):
+    new_field = []
+    for r in range(nrows):
+        nrow = []
+        for c in range(ncols):
+            count = 0
+            for nb in [(-1, 0), (-1, 1), (0, 1), (1, 1), (1, 0), (1, -1), (0, -1), (-1, -1)]:
+                nr = r + nb[0]
+                nc = c + nb[1]
+                if nr < 0 or nr >= nrows or nc < 0 or nc >= ncols:
+                    continue
+                if rows[nr][nc] == "#":
+                    count += 1
+            if rows[r][c] == "#" and (count == 2 or count == 3):
+                nrow.append("#")
+            elif rows[r][c] == "." and count == 3:
+                nrow.append("#")
+            else:
+                nrow.append(".")
+        new_field.append(nrow)
+    rows = new_field
+    if part_2:
+        rows[0][0] = "#"
+        rows[0][ncols - 1] = "#"
+        rows[nrows - 1][0] = "#"
+        rows[nrows - 1][ncols - 1] = "#"
+
+r = 0
+for row in rows:
+    for c in row:
+        if c == "#":
+            r += 1
+print(r)

2015/d19.py

@@ -0,0 +1,41 @@
+import sys
+from random import shuffle
+
+data = open(0).read().strip()
+
+eqs = []
+text = ""
+for line in data.splitlines():
+    if "=>" in line:
+        lhs, rhs = line.split(" => ")
+        eqs.append((lhs, rhs))
+    elif line:
+        text = line
+
+molecules = set()
+for lhs, rhs in eqs:
+    for i in range(len(text)):
+        f, t = text[:i], text[i:]
+        if t.startswith(lhs):
+            n = f + t.replace(lhs, rhs, 1)
+            molecules.add(n)
+print(len(molecules))
+
+# m = float("inf")
+# for _ in range(100000):
+#     getout = False
+#     c = str(text)
+#     for i in range(10**4):
+#         if i % 1000 == 0:
+#             shuffle(eqs)
+#         for lhs, rhs in eqs:
+#             if rhs in c:
+#                 c = c.replace(rhs, lhs, 1)
+#                 if c == "e":
+#                     if i < m:
+#                         m = i
+#                         print(i)
+#                     getout = True
+#         if getout:
+#             break
+# print(m)

README.md

@@ -19,4 +19,9 @@ written in Python.
 - Day 12: 6:03
 - Day 13: 7:06 (would have been first by a minute, probably 70ish in 2023)
 - Day 14: 27:45 ... that was weak, logic error for part 2 :/
-- Day 15:
+- Day 15: 16:00 I should probably stop brute forcing these optimization problems
+- Day 16: 19:00
+- Day 17: 9:05
+- Day 18: 10:39
+- Day 19:
+- Day 20: