12-1.py

import json

total = 0;

def traverse_list(l):
    global total
    for item in l:
        if isinstance(item, int):
            total += item
        elif isinstance(item, str):
            pass
        elif isinstance(item, list):
            traverse_list(item)
        elif isinstance(item, dict):
            traverse_dict(item)

def traverse_dict(d):
    global total
    for k, v in d.iteritems():
        if isinstance(v, int):
            total += v
        elif isinstance(v, str):
            pass
        elif isinstance(v, list):
            traverse_list(v)
        elif isinstance(v, dict):
            traverse_dict(v)

with open('day12.txt', 'r') as f:
    input = json.load(f)
    if isinstance(input, list):
        traverse_list(input)
    elif isinstance(input, dict):
        traverse_dict(input)

print total