《离散化＋前缀和》

#include <bits/stdc++.h>
using namespace std;
const int N = 300010;
typedef pair<int, int> PII;
int a[N], s[N];
vector<int> alls;
vector<PII> add, query;
int find(int x)
{
    int l = 0, r = alls.size() - 1;
    while (l < r) {
        int mid = l + r >> 1;
        if (alls[mid] >= x) r = mid;
        else l = mid + 1;
    }
    return r + 1;
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < n; i ++) {
        int x, c;
        cin >> x >> c;
        add.push_back({x, c});
        alls.push_back(x);
    }
    for (int i = 0; i < m; i ++) {
        int l, r;
        cin >> l >> r;
        query.push_back({l, r});
        alls.push_back(l);
        alls.push_back(r);
    }
    sort(alls.begin(), alls.end());
    alls.erase(unique(alls.begin(), alls.end()), alls.end());
    for (auto item : add) {
        int x = find(item.first);
        a[x] += item.second;
    }
    for (int i = 1; i <= alls.size(); i ++) {
        s[i] = s[i - 1] + a[i];
    }
    for (auto item : query) {
        int l = find(item.first),r = find(item.second);
        cout << s[r] - s[l - 1] << endl;
    }
    return 0;
}