第一题:Java import java.util.HashMap; import java.util.Map; import java.util.Scanner; public class Baidu { public static void main(String[] args) { int res = 0; Scanner in = new Scanner(System.in); // 员工数 int n = in.nextInt(); // 种类 int k = in.nextInt(); // 每一个员工喜欢的饮料 int[] drinks = new int[n]; for (int i = 0; i < n; i++) { drinks[i] = in.nextInt(); } Map<Integer, Integer> map = new HashMap(); for (int i = 0; i < drinks.length; i++) { if (map.containsKey(drinks[i])) { if (map.get(drinks[i]) - 1 >= 0 ) { map.put(drinks[i], map.get(drinks[i]) - 1); } else { map.put(drinks[i], map.get(drinks[i]) + 1); res += 1; } } else { map.put(drinks[i], 1); res += 1; } } System.out.println(res); } }