最少按键次数

/*
 * Leetcode Problem 2268: Minimum Key Presses
 * Using Java Stream to find the minimum key presses needed to type a list of words.
 * Each key press corresponds to a character, with the last few typed characters being free.
 */

import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class Solution {
    public int minimumKeyPresses(String[] words) {
        // Stream through the array of words, split them into characters, and collect unique characters
        Set<Character> uniqueChars = Stream.of(words)
            .flatMapToInt(String::chars) // Convert each word to IntStream of chars
            .mapToObj(c -> (char) c) // Map to Character objects
            .collect(Collectors.toSet()); // Collect into a set of unique characters

        // The number of unique characters is the number of key presses required
        return uniqueChars.size();
    }
}