day7-1.py

processed_lines = []
known_keys = []
mapping = {}

def is_entire_lhand_known(line):
    ops = ('OR', 'AND', 'NOT', 'LSHIFT', 'RSHIFT')
    keys = []
    for part in [x.strip() for x in line[:line.index('->')].split()]:
        if part not in ops and not part.isdigit():
            keys.append(part)
    return all([k in known_keys for k in keys])

def is_number_signal_provider(line):
    return line.split()[0].isdigit() and len(line.split()) == 3 and line.split()[1] == '->'
    
def process_line(line):
    instructions = line.strip().split()
    target = instructions[-1]
    
    if instructions[1] == 'RSHIFT':
        first = instructions[0]
        second = instructions[2]
        if first.isdigit() and not second.isdigit():
            value = first / 2**int(second)
        elif not first.isdigit() and second.isdigit():
            value = mapping[first] / 2**int(second)
        else:
            value = mapping[first] / 2**int(second)                
        mapping[target] = value
    elif instructions[1] == 'LSHIFT':
        first = instructions[0]
        second = instructions[2]
        value = mapping[first] * 2**int(second)
        mapping[target] = value
    elif instructions[1] == 'AND':
        first = instructions[0]
        second = instructions[2]
        if first.isdigit() and not second.isdigit():
            value = int(first) & mapping[second]
        elif not first.isdigit() and second.isdigit():
            value = mapping[first] & second
        else:
            value = mapping[first] & mapping[second]
        mapping[target] = value
    elif instructions[1] == 'OR':
        first = instructions[0]
        second = instructions[2]
        value = mapping[first] | mapping[second]
        mapping[target] = value
    elif instructions[0] == 'NOT':
        mapping[target] = 65535 - mapping[instructions[1]]
    else:  # provide signal to target wire.
        value = mapping[instructions[0]]
        mapping[target] = value
        known_keys.append(target)
    
    known_keys.append(target)
    

with open('day7.txt', 'r') as f:
    s = f.readlines()
    while len(s) > len(processed_lines):
        for line in [l.strip() for l in s]:
            
            if line in processed_lines:
                continue

            if is_number_signal_provider(line):
                instructions = line.strip().split()
                target = instructions[-1]
                value = int(instructions[0])
                mapping[target] = value
                known_keys.append(target)
                processed_lines.append(line)
                continue
            
            if is_entire_lhand_known(line):
                process_line(line)
                processed_lines.append(line)

print mapping['a']