Solve day 7 and 8 of 2018.

2018/d8.py

@@ -0,0 +1,59 @@
+from lib import *
+
+
+def parse(fields, i):
+    n_children = fields[i]
+    n_meta = fields[i + 1]
+    i += 2
+    children = []
+    meta_score = 0
+    for _ in range(n_children):
+        c, i, m = parse(fields, i)
+        children.append(c)
+        meta_score += m
+    for i in range(i, i + n_meta):
+        meta_score += fields[i]
+    i += 1
+    return children, i, meta_score
+
+
+def parse2(fields, i):
+    n_children = fields[i]
+    n_meta = fields[i + 1]
+    i += 2
+    children = []
+    scores = []
+    for _ in range(n_children):
+        c, i, s = parse2(fields, i)
+        children.append(c)
+        scores.append(s)
+
+    score = 0
+    if n_children == 0:
+        for j in range(i, i + n_meta):
+            score += fields[j]
+    else:
+        for j in range(i, i + n_meta):
+            new_i = fields[j]
+            new_i -= 1
+            if new_i < 0:
+                continue
+            if new_i < len(children):
+                score += scores[new_i]
+    i += n_meta
+    return children, i, score
+
+
+def main():
+    input_file = __file__.replace(".py", ".txt")
+    with open(input_file) as f:
+        data = f.read()
+    nums = str_to_ints(data)
+    tree = parse(nums, 0)
+    print(tree[2])
+    tree = parse2(nums, 0)
+    print(tree[2])
+
+
+if __name__ == "__main__":
+    main()