day18/badmath2.py

   1 #!/usr/bin/python3
   2
   3 import sys
   4
   5 filename="p1_71.txt"
   6 if len(sys.argv) > 1:
   7     filename=sys.argv[1]
   8
   9 def parse_sum(oursum):
  10     parts = oursum.split()
  11     new_parts=[]
  12
  13     for part in parts:
  14         if part[0]=="(":
  15             for index,c in enumerate(part):
  16                 if c=="(":
  17                     new_parts.append("(")
  18                 else:
  19                     new_parts.extend(parse_sum(part[index:]))
  20                     break
  21         elif part[-1]==")":
  22             got_number=False
  23             for index,c in enumerate(part):
  24                 if c==")":
  25                     if not got_number:
  26                         new_parts.extend(parse_sum(part[0:index]))
  27                         got_number=True
  28                     new_parts.append(c)
  29         elif part in ['+','*']:
  30             new_parts.append(part)
  31         else:
  32             new_parts.append(int(part))
  33     return new_parts
  34
  35 def do_sum(parts):
  36     cur_total=0
  37     next_oper="+"
  38     bracketed=[]
  39     in_brackets=0
  40     new_parts=[]
  41
  42     # first do all bracketed parts
  43     for part in parts:
  44         if in_brackets > 0 and part != ")" and part != "(":
  45             bracketed.append(part)
  46             continue
  47         if in_brackets > 0 and part == ")":
  48             in_brackets-=1
  49             bracketed.append(part)
  50             if in_brackets == 0:
  51                 part=do_sum(bracketed[1:-1])
  52                 bracketed.clear()
  53             else:
  54                 continue
  55         if part == "(":
  56             in_brackets+=1
  57             bracketed.append(part)
  58             continue
  59         new_parts.append(part)
  60
  61     while "+" in new_parts:
  62         plus_index = new_parts.index("+")
  63         left=new_parts[plus_index-1]
  64         right=new_parts[plus_index+1]
  65         new_new_parts=new_parts[:plus_index-1]
  66         new_new_parts.append(left+right)
  67         new_new_parts.extend(new_parts[plus_index+2:])
  68         new_parts=new_new_parts
  69
  70     cur_total=new_parts[0]
  71
  72     # now we should just be able to go through new_parts left to right
  73     for part in new_parts[1:]:
  74         if part == '*':
  75             continue
  76         else:
  77             cur_total*=int(part)
  78
  79     return cur_total
  80
  81 total=0
  82 total2=0
  83 for line in [line.rstrip() for line in open(filename, "r")]:
  84     answer=do_sum(parse_sum(line))
  85     total+=answer
  86
  87 print("Part 2 Total:", total)