题解

#include <bits/stdc++.h>
using namespace std;
#define read cin
#define written cout
struct Log {
	int day, cow, change;
};

int main() {
	int n;
	int g;
	read >> n >> g;

	vector<Log> log(n);
	map<int, int> cows;
	for (Log &l : log) {
		read >> l.day >> l.cow >> l.change;
		cows[l.cow] = g;
	}
	sort(log.begin(), log.end(),
	          [](const Log &l1, const Log &l2) { return l1.day < l2.day; });

	map<int, int> milk_prod{{g, n}};

	int changeAmt = 0;
	for (Log l : log) {
		int milk_amt = cows[l.cow];
		bool was_top = milk_amt == milk_prod.rbegin()->first;
		int prev_count = milk_prod[milk_amt];
		milk_prod[milk_amt]--;
		if (milk_prod[milk_amt] == 0) { milk_prod.erase(milk_amt); }
		milk_amt += l.change;
		cows[l.cow] = milk_amt;
		milk_prod[milk_amt]++;

		bool is_top = milk_amt == milk_prod.rbegin()->first;
		int curr_count = milk_prod[milk_amt];
		if (was_top) {
			if (is_top && curr_count == prev_count) { continue; }
			changeAmt++;
		} else if (is_top) {
			changeAmt++;
		}
	}

	written << changeAmt << endl;
}