牛客网真题-48-脸滚键盘

本题显然想到用hashmap,ascii字符作为key的HashMap都可以用int[128]代替
两次遍历即可,本题注意每一行输入数据的处理即可

import java.util.*;

public class Main {
    public static String indexOfFirstK(String s, int k){
        int[] ascii = new int[128];
        int cnt = k;

        for(int i = 0; i < s.length(); i++){
            ascii[s.charAt(i)]++;
        }
        for(int i = 0; i < s.length(); i++){
            if(ascii[s.charAt(i)] == 1){
                cnt--;
                if(cnt == 0){
                    return "[" + s.charAt(i) + "]";
                }
            }
        }
        return "Myon~";
    }


    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNext()) {
            String s = scanner.nextLine();
            int k = Integer.parseInt(s.split(" ")[0]);

            s = s.substring(s.split(" ")[0].length() + 1);
            System.out.println(indexOfFirstK(s, k));
        }
    }
}