day3.py

gistfile1.txt

import re

with open('input.txt', 'r') as f:
    lines = f.readlines()
  
def get_symbols(lines):
    symbols = []
    all_lines = " ".join(line.strip() for line in lines)  
    for c in all_lines:
        if (c not in symbols) and (not c.isdigit()):
            symbols.append(c)
    symbols.remove('.') 
    return symbols

SYMBOLS = get_symbols(lines)

l = len(lines[0])


def get_locations(line,regex=False):
    pattern = r'\b\d+\b'
    return [(m.start(0), m.end(0)) for m in re.finditer(pattern, line)]
   

def adjusted_lines(i, lines):
    current_line = '.' + lines[i] + '.'
    if i == 0:
        previous_line = '.'*len(current_line)
    else:
        previous_line = '.' + lines[i-1] + '.'
   
    if i == len(lines)-1:
        next_line = '.'*len(current_line)
    else:
        next_line = '.' + lines[i+1] + '.'
        
    return previous_line, current_line, next_line

def get_surroundings(previous_line, current_line, next_line, start, finish):
    left_position = start 
    right_position = finish + 2
    
    upper_line = previous_line[left_position:right_position]
    this_line = current_line[left_position:right_position]
    lower_line = next_line[left_position:right_position]
    surroundings = this_line+lower_line+upper_line
    return surroundings
    
def get_number_to_add(i, lines, number_position, symbols=SYMBOLS):
    start, finish = number_position 
    
    previous_line, current_line, next_line = adjusted_lines(i, lines)
    surroundings = get_surroundings(previous_line, current_line, next_line, start, finish)

    # print("Upper", upper_line, f"    {i}", left_position, right_position, number_size)
    # print("this ", this_line, f"    {any(e in symbols for e in surroundings)}")
    # print("lower", lower_line)
    # print("$$$$$$$$$$$$$$$$$$$$$$$$-")
    valid = any(e in symbols for e in surroundings)
    
    
    if valid:
        return int(lines[i][start:finish])
    else:
        return 0
    

def symbol_position(line, start, i):
    position = line.find('*')
    if position > -1:
        position = start + position
        return (i, position)
    else :
        return None
    
def all_positions(upper_line, this_line, lower_line, start, i):
    positions = []
    upper_pos = symbol_position(upper_line, start, i-1)
    this_pos = symbol_position(this_line, start, i)
    lower_pos = symbol_position(lower_line, start, i+1)
    if upper_pos:
        positions.append(upper_pos)
    if this_pos:
        positions.append(this_pos)
    if lower_pos:
        positions.append(lower_pos)
    return positions
    
def get_number_to_add_with_position(i, lines, number_position, symbols=SYMBOLS):
    start, finish = number_position 
    number = int(lines[i][start:finish])

    previous_line, current_line, next_line = adjusted_lines(i, lines)
    
    left_position = start 
    right_position = finish + 2
    
    upper_line = previous_line[left_position:right_position]
    this_line = current_line[left_position:right_position]
    lower_line = next_line[left_position:right_position]
    surroundings = this_line+lower_line+upper_line
    valid = any(e in symbols for e in surroundings)
    
    if valid:
        
        positions = all_positions(upper_line, this_line, lower_line, start, i)
        
        return int(lines[i][start:finish]), positions
    else:
        return 0, []

total = 0
for i, line in enumerate(lines):
    locations = get_locations(line)
    for location in locations:       
        number = get_number_to_add(i, lines, number_position=location)
        total += int(number)
        
my_dict = {}

total_2 = 0
for i, line in enumerate(lines):
    locations = get_locations(line)
    for location in locations:       
        number, positions = get_number_to_add_with_position(i, lines, number_position=location, symbols=['*'])
        for pos in positions:
            if pos in my_dict:
                my_dict[pos].append(number)
            else:
                my_dict[pos] = [number]
               
for key, value in my_dict.items():
    if len(value) == 2:
        total_2 += value[0]*value[1]

print("Part 1", total)
print("Part 2", total_2)