真的想了蛮久的了还是想不通（

官方题解 做法，为了避免讨论区题解我就不详细写方法了，如果您有哪点不懂我在干啥可以直接问。

怀疑是 std::set::upper_bound 的锅。

#include <set>
#include <cstdio>
#include <algorithm>
const int N = 2e5 + 10; 
struct node
{ 
    int u, v, n;
    bool operator<(const node& x) const { return u < x.u; } 
    bool operator>(const node& x) const { return u > x.u; } 
    bool operator==(const node& x) const { return u == x.u; }
    bool operator!=(const node& x) const { return u != x.u; }
}c[N], a[N]; int tc, ta;
std::set<node> s;
int main()
{
    int n; scanf("%d", &n);
    for (int i = 1; i <= n; ++i) 
    {
        int q; scanf("%d", &q);
        if (q == 1) ++tc, scanf("%d%d%d", &c[tc].u, &c[tc].v, &c[tc].n);
        else ++ta, scanf("%d%d%d", &a[ta].u, &a[ta].v, &a[ta].n);
    }
    for (int i = 1; i <= tc; ++i)
    {
        int t = c[i].u, x = c[i].v;
        c[i].u = t + x; c[i].v = t - x;
    }
    for (int i = 1; i <= ta; ++i)
    {
        int t = a[i].u, x = a[i].v;
        a[i].u = t + x; a[i].v = t - x;
    }
    auto cmp = [](const node& x, const node& y) { return x.v < y.v; };
    std::sort(a + 1, a + ta + 1, cmp);
    std::sort(c + 1, c + tc + 1, cmp);
    int now = 1, ans = 0;
    for (int i = 1; i <= ta; ++i)
    {
        while (now <= tc && c[now].v <= a[i].v) s.insert(c[now++]);
        auto tmp = s.upper_bound(a[i]);
        if (tmp == s.begin()) continue;
        --tmp;
        while (true)
        {
            auto p = *tmp; s.erase(tmp);
            int minx = std::min(a[i].n, p.n);
            a[i].n -= minx; p.n -= minx; ans += minx;   
            if (p.n) s.insert(p); if (!a[i].n) break;
            tmp = s.upper_bound(a[i]);
            if (tmp == s.begin()) break;
            --tmp;
        }
    }
    printf("%d\n", ans); return 0;
}