Initials From a Name

Problem

Take the first letter of each word in full_name, uppercase it, and join the letters. Words are separated by one or more spaces.

Implement initials(full_name).

full_name: A name made of letters and spaces.

Return the initials, for example "ADL".

1 ≤ length of full_name ≤ 200; it contains at least one letter

Example 1

Input:
full_name = "Ada Lovelace"

Expected output:
expected = "AL"

Input:
std::string full_name = "Ada Lovelace";

Expected output:
std::string expected = "AL";

Input:
string full_name = "Ada Lovelace";

Expected output:
string expected = "AL";

A from Ada and L from Lovelace: "AL".

Example 2

Input:
full_name = "grace  brewster  hopper"

Expected output:
expected = "GBH"

Input:
std::string full_name = "grace  brewster  hopper";

Expected output:
std::string expected = "GBH";

Input:
string full_name = "grace  brewster  hopper";

Expected output:
string expected = "GBH";

Extra spaces don't matter; the initials are uppercased: "GBH".

Try on your own first, then open one hint at a time.

Hint 1

Each word contributes exactly one character: its first letter.

Hint 2

Traverse the name while tracking when a new word starts after spaces.

Hint 3

Watch for multiple spaces in a row so you only take one initial per word.

Expected complexity

O(n) time, O(1) extra space

This challenge is adapted for CodeUtility. Follow the statement and constraints above.