Problema
Return the index of the first character in text that appears exactly once. Case matters.
Implement first_unique_index(text).
Input
text: The text to inspect.
Output
Return the index, or -1 if every character repeats.
Vincoli
0 ≤ length ≤ 100,000
Esempi
Esempio 1
Input:
text = "swiss"
Output atteso:
expected = 1Input:
std::string text = "swiss";
Output atteso:
long long expected = 1;Input:
string text = "swiss";
Output atteso:
long expected = 1;Spiegazione
s repeats, w appears once at index 1.
Esempio 2
Input:
text = "aabb"
Output atteso:
expected = -1Input:
std::string text = "aabb";
Output atteso:
long long expected = -1;Input:
string text = "aabb";
Output atteso:
long expected = -1;Spiegazione
Every character repeats: -1.
Come affrontarlo
Prova prima da solo, poi apri un suggerimento alla volta.
Suggerimento 1
You need characters that appear exactly once, not just the first different one.
Suggerimento 2
Count all character frequencies first, then find the earliest position with frequency one.
Suggerimento 3
Remember that uppercase and lowercase letters are different characters.
Complessità attesa
O(n) time, O(k) extra space
Riferimenti
Questa sfida è adattata per CodeUtility. Segui la traccia e i vincoli sopra.