From d76ed4a9b39d203e987f8aa4982ea09dc15745fa Mon Sep 17 00:00:00 2001
From: Ben Charlton <ben@spod.cx>
Date: Wed, 16 Dec 2020 23:19:29 +0000
Subject: [PATCH] day 16

---
 16/16.py | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100644 16/16.py

diff --git a/16/16.py b/16/16.py
new file mode 100644
index 0000000..6da5bb5
--- /dev/null
+++ b/16/16.py
@@ -0,0 +1,89 @@
+#!/usr/bin/python3
+
+import sys, re
+
+rules = {}
+invalid = 0
+unpossible = {}
+opts = 0
+myticket = None
+
+for line in sys.stdin:
+    line = line.rstrip()
+    m = re.match(r'^([^:]+): (\d+)-(\d+) or (\d+)-(\d+)$', line)
+    if m is not None:
+        rules[m.group(1)] = [int(m.group(2)),int(m.group(3)),int(m.group(4)),int(m.group(5))]
+
+    m = re.match(r'^([\d+,])+$', line)
+    if m is not None:
+        values = line.split(',')
+        if myticket is None:
+            myticket = values
+
+        # Part 1
+        skip = False
+        for v in values:
+            v = int(v)
+            valid = 0
+            for r in rules:
+                k = rules[r]
+                if k[0] <= v <= k[1] or k[2] <= v <= k[3]:
+                    valid += 1
+
+            if valid == 0:
+                invalid += v
+                skip = True
+        if skip:
+            continue
+    
+
+        # Part 2
+        for i,v in enumerate(values):
+            v = int(v)
+
+            for r in rules:
+                k = rules[r]
+                if not (k[0] <= v <= k[1] or k[2] <= v <= k[3]):
+                    if r in unpossible:
+                        unpossible[r].append(i)
+                    else:
+                        unpossible[r] = [i]
+
+        opts = len(values)
+
+# dirty hacks done dirt cheap.
+possible = {}
+for r in rules:
+
+    if r in unpossible:
+        poss = unpossible[r]
+    else: 
+        poss = []
+
+    t = []
+    for i in range(opts):
+        if i not in poss:
+            t.append(i)
+    possible[r] = t
+
+
+final = {}
+used = {}
+for rules in sorted(possible, key=lambda key: len(possible[key])):
+    #print(rules, possible[rules])
+    if rules not in final:
+        for i in possible[rules]:
+            if i not in used:
+                final[rules] = i
+                used[i] = 1
+                break
+
+
+r2 = 1
+for field in final:
+    #print(field, final[field], myticket[final[field]])
+    if field.startswith('departure'):
+        r2 *= int(myticket[final[field]])
+        
+print(1, invalid)
+print(2, r2)
\ No newline at end of file