Data Structures

N/A

Parsing

Nothing special, forward as is

Part 1

Extract a number from each line, alphabets are useless

Need a two digit number

rr123rr37t => 17
rr8t => 88

gist : Find a number once from the front and once from the back

Approach 1

Treating string as []byte, (for i:= 0; i <....)

Easy but incorrect for edge cases

Does not deal properly with non-alphanumeric characters which take more than 1 byte

Approach 2

Treating string as []rune, (for _, r := range)

Correct

But did not want to deal with reversing the string to get the last digit

Part 2

Extract a number from each line, alphabets can be numbers spelled out

Need a two digit number

a1onetwo7three => 13
aonenine => 19

gist : Replace words with numbers, then do Part 1

Approach 1

Replace words with corresponding number, (one => 1)

Incorrect

Direct replacing will fail as words might overlap

twone => 2ne => 2
BUT
twone => 21

Approach 2

Replace words with corresponding number and the word, (one => one1one)

Correct

Hacky but works 🤷‍♀️

twone => twone1one => two2twone1one
OR
twone => two2twone => two2twone1one

Verified that order does not matter as long as we are replacing only once