贪心

策略就是每次卖给别人品质最差的奶牛，用multiset

#include <iostream>
#include <set>

const int maxn = 1e6 + 5;

int n, op[maxn], num[maxn], ans;

int main() {
    using std::cin;
    using std::cout;
    using std::endl;
    
    std::ios::sync_with_stdio(false);

    cin.tie(nullptr);

    cin >> n;

    std::multiset<int> s;
    
    for(int i = 1; i <= n; i++) cin >> op[i] >> num[i];
    
    for(int i = n; i >= 1; i--) {
        if(op[i] == 1) {
            s.insert(num[i]);
        } else if(!s.empty()) {
            auto iter = s.lower_bound(num[i]);
            if(iter == s.end()) iter--;
            for(;;) {
                if(*iter <= num[i]) {
                    ans++;
                    s.erase(iter);
                    break;
                }
                if(iter == s.begin()) break;
                iter--;
            };
        }
    }
    
    cout << ans << endl;

    return 0;
}