First Unique Character Programming Challenge

Problem

Return the index of the first character in text that appears exactly once. Case matters.

Implement first_unique_index(text).

text: The text to inspect.

Return the index, or -1 if every character repeats.

0 ≤ length ≤ 100,000

Example 1

Input:
text = "swiss"

Expected output:
expected = 1

Input:
std::string text = "swiss";

Expected output:
long long expected = 1;

Input:
string text = "swiss";

Expected output:
long expected = 1;

s repeats, w appears once at index 1.

Example 2

Input:
text = "aabb"

Expected output:
expected = -1

Input:
std::string text = "aabb";

Expected output:
long long expected = -1;

Input:
string text = "aabb";

Expected output:
long expected = -1;

Every character repeats: -1.

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