Day 16

day16/shared.py

@@ -0,0 +1,48 @@
+def bin_to_int(bin_num):
+    return int(bin_num, 2)
+
+
+def parse_literal(bin_num):
+    res = ""
+    i = 0
+    while True:
+        res += bin_num[i+1:i+5]
+        i += 5
+        if bin_num[i-5] == '0':
+            break
+    return bin_to_int(res), i
+
+
+def parse_op(bin_num):
+    if bin_num[0] == '0':
+        length = bin_to_int(bin_num[1:16])
+        return parse_packets(bin_num[16:16+length]), length+16
+    else:
+        amount = bin_to_int(bin_num[1:12])
+        pkgs = []
+        i = 0
+        for _ in range(amount):
+            pkg, length = parse_packet(bin_num[12+i:])
+            pkgs.append(pkg)
+            i += length
+        return pkgs, 12+i
+
+
+def parse_packet(bin_num):
+    ver = bin_to_int(bin_num[:3])
+    op = bin_to_int(bin_num[3:6])
+    if op == 4:
+        value, length = parse_literal(bin_num[6:])
+    else:
+        value, length = parse_op(bin_num[6:])
+    return (ver, op, value), length + 6
+
+
+def parse_packets(bin_num):
+    pkgs = []
+    i = 0
+    while '1' in bin_num[i:]:
+        pkg, length = parse_packet(bin_num[i:])
+        pkgs.append(pkg)
+        i += length
+    return pkgs