再次复习离散化，每次复习，都有不一样的收获。曾经刚学算法的时候，我自作聪明为了省20w的空间，写了很多复杂的代码。现在看来，y总的做法真的简洁巧妙，虽然多了20w空间，但是减少了很多思维难度，而我当时却为了一点蝇头小利，多走弯路，并沾沾自喜，今天看来属实惭愧。还是要低下头，虚心学习，慢慢进步。下面奉献上我的Java代码。

Java的去重我是这样写的：alls = new ArrayList<>(new TreeSet<>(alls));

import java.io.*;
import java.util.ArrayList;
import java.util.Objects;
import java.util.TreeSet;

public class Main {
    static final int N = 300010;
    static int[] a = new int[N], s = new int[N];
    static int n, m;
    static ArrayList<Integer> alls = new ArrayList<>();
    static ArrayList<Pair> add = new ArrayList<>(), query = new ArrayList<>();
    static int find(int x) {
        int l = 0, r = alls.size() - 1;
        while (l < r) {
            int mid = l + r >> 1;
            if (alls.get(mid) >= x) r = mid;
            else l = mid + 1;
        }
        return l;
    }
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        String[] in = br.readLine().split(" ");
        n = Integer.parseInt(in[0]);
        m = Integer.parseInt(in[1]);
        for (int i = 0; i < n; i++) {
            int x, c;
            in = br.readLine().split(" ");
            x = Integer.parseInt(in[0]);
            c = Integer.parseInt(in[1]);
            add.add(new Pair(x, c));
            alls.add(x);
        }
        alls.add(-2000000000);
        for (int i = 0; i < m; i++) {
            int l, r;
            in = br.readLine().split(" ");
            l = Integer.parseInt(in[0]);
            r = Integer.parseInt(in[1]);
            query.add(new Pair(l, r));
            alls.add(l);
            alls.add(r);
        }
        alls = new ArrayList<>(new TreeSet<>(alls));
        for (Pair p : add) {
            int x = p.x, c = p.y;
            x = find(x);
            a[x] += c;
        }
        for (int i = 1; i <= alls.size(); i++) s[i] = s[i - 1]  + a[i];
        for (Pair p : query) {
            int l = p.x, r = p.y;
            l = find(l);
            r = find(r);
            bw.write(String.format("%d\n", s[r] - s[l - 1]));
        }
        bw.flush();
    }
}

class Pair {
    public int x;
    public int y;

    public Pair(int x, int y) {
        this.x = x;
        this.y = y;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Pair pair = (Pair) o;
        return x == pair.x && y == pair.y;
    }

    @Override
    public int hashCode() {
        return Objects.hash(x, y);
    }
}