Medium20 min

First Unique Character

Return the first character that appears exactly once, or null if there is none.

Your function

Implement solve(value, extra) in JavaScript. Return the answer; printing alone does not count as a result.

Examples

Input: ["swiss"]
Output: "w"
Input: ["aabb"]
Output: null

Constraints

Input contains at most 1,000 values or characters. Numbers are finite integers. Inputs follow the structure shown in the examples.

13px
main.jsYour ideas, in code.
Loading your editor…
Run your code to see the output here.
Ready to buildUTF-84 lines

Test freely without an account. Signed-in submissions are checked independently by the isolated execution service before progress is awarded.