DAY 27 OF 90 · Walk the string

First repeat

Easy90 Days of Looping

Inputs

text is 0 to 16 lowercase letters (a to z).

Create an empty string seen that will hold the letters you have already visited.
Use a loop over text. If the current character is already in seen, return it right away. Otherwise add it to seen.
Complete firstRepeat so it returns the first letter that shows up a second time, or an empty string. Return it, do not print it.

With text = "abcbad", firstRepeat returns "b".

TEST DATA 1: text is "abcbad"

TEST DATA 2: text is "abc"

Text is just a list of characters, so everything you know about lists applies. String problems in interviews are array problems with letters.

DAY 27 OF 90 · Walk the string

Easy90 Days of Looping

text is 0 to 16 lowercase letters (a to z).

Create an empty string seen that will hold the letters you have already visited.
Use a loop over text. If the current character is already in seen, return it right away. Otherwise add it to seen.
Complete firstRepeat so it returns the first letter that shows up a second time, or an empty string. Return it, do not print it.

With text = "abcbad", firstRepeat returns "b".

TEST DATA 1: text is "abcbad"

TEST DATA 2: text is "abc"

Text is just a list of characters, so everything you know about lists applies. String problems in interviews are array problems with letters.