Day 01: Trebuchet?!

Official Problem Page

Use Regular Expressions with lookahead to not consume matches. This allows for overlapping matches, which is important for part two.

Example: eightwo will match both eight and two. Without lookahead, the string eight would be consumed, causing a missed match on the remaining wo.

Part 1

from re import findall
 
input = open("input/1.txt", "r").readlines()
 
pattern = r"(?=(\d)){1}"
 
result = 0
for line in input:
    match = findall(pattern, line)
    result += int(match[0] + match[-1])
print(result)

Part 2

mapping = {
    "one": "1",
    "two": "2",
    "three": "3",
    "four": "4",
    "five": "5",
    "six": "6",
    "seven": "7",
    "eight": "8",
    "nine": "9",
    "1": "1",
    "2": "2",
    "3": "3",
    "4": "4",
    "5": "5",
    "6": "6",
    "7": "7",
    "8": "8",
    "9": "9",
}
 
pattern = rf"(?=({'|'.join(mapping)})){{1}}"
 
result = 0
for line in input:
    match = findall(pattern, line)
    result += int(mapping.get(match[0]) + mapping.get(match[-1]))
print(result)