Add code for day 7

[advent-of-code-2020.git] / day07 / bags.py

diff --git a/day07/bags.py b/day07/bags.py
new file mode 100755 (executable)
index 0000000..bedd6e8
--- /dev/null
+++ b/day07/bags.py
@@ -0,0 +1,67 @@
+#!/usr/bin/python3
+
+import re
+
+contained_by={}
+contains={}
+
+for rule in open("input.txt", "r"):
+    rule=rule.rstrip()
+    print("Rule: {}".format(rule))
+    m=re.match("^(.*?) bag(s|) contain (.*)$", rule)
+    if m:
+        bag=m.group(1)
+        contain=m.group(3).split(", ")
+        for contained in contain:
+            m2=re.match('^([0-9]*) (.*?) bag(s|).*$', contained)
+            if m2 is not None:
+                bag_count=int(m2.group(1))
+                bag_name=m2.group(2)
+                if not bag in contains:
+                    contains[bag]=[]
+                contains[bag].append((bag_count, bag_name))
+                if not bag_name in contained_by:
+                    contained_by[bag_name] = []
+                if not bag in contained_by[bag_name]:
+                    contained_by[bag_name].append(bag)
+
+looking_for="shiny gold"
+
+bags=[]
+for bag in contained_by[looking_for]:
+    if bag not in bags:
+        bags.append(bag)
+
+print(bags)
+
+new_bags=True
+new_bag_list=[b for b in bags]
+new_new_bag_list=[]
+while new_bags:
+    for bag1 in new_bag_list:
+        if bag1 not in contained_by:
+            continue
+        for bag2 in contained_by[bag1]:
+            if bag2 not in bags:
+                new_new_bag_list.append(bag2)
+                bags.append(bag2)
+    if (len(new_new_bag_list) > 0):
+        new_bag_list=[b for b in new_new_bag_list]
+        new_new_bag_list=[]
+        new_bags=True
+    else:
+        new_bag_list=[]
+        new_bags=False
+
+print("Found {} bags that can contain {} bags".format(len(bags), looking_for))
+
+def get_count(bag_name):
+    count=0
+    if not bag_name in contains:
+        return 0
+    for (num,bag) in contains[bag_name]:
+        count+=(get_count(bag)+1)*num
+    return count
+
+# now looking for how many bags in bags we're looking for
+print("Contains {} bags".format(get_count(looking_for)))