对于本题,java必须运用快读否则将会超时: 不用快读：

import java.io.*;
import java.util.*;

public class Main {

    static TreeMap<Integer, Integer> tl = new TreeMap<>(), tr = new TreeMap<>();
    public static void main(String[] args) throws IOException {
        Scanner sc=new Scanner(System.in);
        int T = sc.nextInt();
        while (T-- > 0) {
            char ch = sc.next().charAt(0);
            int l = sc.nextInt();
            int r = sc.nextInt();
            if (ch == '+') {
                tl.put(l, tl.getOrDefault(l, 0) + 1);
                tr.put(r, tr.getOrDefault(r, 0) + 1);
            } else {
                tl.put(l, tl.getOrDefault(l, 0) - 1);
                tr.put(r, tr.getOrDefault(r, 0) - 1);
                if (tl.get(l) == 0) tl.remove(l);
                if (tr.get(r) == 0) tr.remove(r);
            }
            System.out.println(tl.size() > 0 && tr.size() > 0 && tl.lastKey() > tr.firstKey() ? "YES" : "NO");
        }
    }
}

运用快读：

import java.io.*;
import java.util.*;

public class Main {

    static BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
    static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
    static TreeMap<Integer, Integer> tl = new TreeMap<>(), tr = new TreeMap<>();

    public static void solve() throws IOException {
        String[] str = bf.readLine().split(" ");
        char ch = str[0].charAt(0);
        int l = Integer.parseInt(str[1]);
        int r = Integer.parseInt(str[2]);
        if (ch == '+') {
            tl.put(l, tl.getOrDefault(l, 0) + 1);
            tr.put(r, tr.getOrDefault(r, 0) + 1);
        } else {
            tl.put(l, tl.getOrDefault(l, 0) - 1);
            tr.put(r, tr.getOrDefault(r, 0) - 1);
            if (tl.get(l) == 0) tl.remove(l);
            if (tr.get(r) == 0) tr.remove(r);
        }
        bw.write(tl.size() > 0 && tr.size() > 0 && tl.lastKey() > tr.firstKey() ? "YES\n" : "NO\n");
    }

    public static void main(String[] args) throws IOException {
        int T = Integer.parseInt(bf.readLine());
        while (T-- > 0) {
            solve();
        }
        bw.close();
    }
}

判断最左边的右端点和最右边的左端点 如果小于，则不相交

#include <iostream>
#include <vector>
#include <set>
using namespace std;
#define int long long
const int mod=1e+7;
signed main() {
    iostream::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int n;
    cin >> n;
    multiset<int> l, r;

    for (int i = 1; i <= n; i++) {
        char c;
        cin >> c;
        int x, y;
        cin >> x >> y;
        if (c == '+') {
            l.insert(x);
            r.insert(y);
        } else {
            l.erase(l.find(x));
            r.erase(r.find(y));
        }
        if (l.size() > 1 && (*r.begin() < *l.rbegin())) {
            cout << "YES" << endl;
        } else {
            cout << "NO" << endl;
        }
    }
    return 0;
 }