The solutions for day 8 of Advent of Code 2020

advent_of_code_day_8_solution.py

def advent_day_8_pt2_solver(instructions):
    N = len(instructions)
    index = 0
    acc = 0
    visited = []
    candidates = []
  
    while index < N:
        if index in visited:
            return acc, candidates, False
        ins = instructions[index]
        sp = ins.split(' ')
        if len(sp) == 1:
            continue
        command = sp[0]
        command_val = int(sp[1])
        if command == 'nop':
            visited.append(index)
            candidates.append(index)
            index += 1
            continue
        if command == 'acc':
            visited.append(index)
            index += 1
            acc += command_val
            continue
        # jump
        visited.append(index)
        candidates.append(index)
        index += command_val
    return acc, candidates, True
    
def advent_day_8_pt2():
    instructions = []
    instructions_orig = []
    with open('input.txt', 'r') as file:
        lst = file.read().split('\n')
        instructions = lst
    instructions_orig = instructions
    instructions.pop()
    res = advent_day_8_pt2_solver(instructions)
    
    if res[2] == False:
        inst = instructions
        for ch_index in res[1]:
            old_instruction = inst[ch_index]
            new_instruction = ""
            
            if "jmp" in old_instruction:
                new_instruction = old_instruction.replace("jmp", "nop")
            else:
                new_instruction = old_instruction.replace("nop", "jmp")
            
            inst[ch_index] = new_instruction
            
            g = advent_day_8_pt2_solver(inst)
            
            if g[2] == True:
                print('suc ', g)
                break
            else:
                inst[ch_index] = old_instruction
        print('done')
    
if __name__ == '__main__':
    advent_day_8_pt2()