题解 | 动态整数集最近值提取

import java.util.*;
public class Main {
    public static void main(String[] args) {
        TreeSet<Integer> set = new TreeSet<>();
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        while (n-- > 0) {
            int op = in.nextInt();
            int x = in.nextInt();
            switch (op) {
                case 1:
                    if (set.contains(x)) {
                        System.out.println("Already Exist");
                    } else {
                        set.add(x);
                    }
                    break;

                case 2:
                    if (set.isEmpty()) {
                        System.out.println("Empty");
                    } else {
                        Integer pre = set.floor(x);
                        Integer next = set.ceiling(x);
                        Integer len1 = 0, len2 = 0;
                        if (pre != null && next != null) {
                            len1 = Math.abs(x - pre);
                            len2 = Math.abs(next - x);
                            if (len1 == len2) {
                                System.out.println(pre);
                                set.remove(pre);
                            } else if (len1 > len2) {
                                System.out.println(next);
                                set.remove(next);
                            } else {
                                System.out.println(pre);
                                set.remove(pre);
                            }
                        } else if (pre == null && next != null) {
                            System.out.println(next);
                            set.remove(next);
                        } else if(pre!=null&&next==null){
                            System.out.println(pre);
                            set.remove(pre);
                        }
                        else{
                            System.out.println(pre);
                            set.remove(pre);
                        }
                    }
                    break;
            }
        }
    }
}