Submission #1104762

# Submission time Handle Problem Language Result Execution time Memory
1104762 2024-10-24T10:34:39 Z Thunnus Job Scheduling (CEOI12_jobs) C++17
100 / 100
302 ms 28628 KB
#include <bits/stdc++.h>
using namespace std;

#define all(x) begin(x), end(x)
#define mp make_pair

using pi = pair<int, int>;
using vi = vector<int>;

int N, D, M;

// test if it is possible to finish the jobs using given # of machines
// return: first: possible or not, second: if possible, the schedule for the
// jobs
pair<bool, vector<vi>> isFeasible(const vector<pi> &jobs, int machineCount) {
	vector<vi> schedule(N);
	int reqNum = 0;
	// we simulate from day 1 until the last day N
	// we move to the next day if all the machines are used or
	// there is no more job requests left on or before this day
	for (int day = 1; day <= N; day++) {
		for (int j = 0; j < machineCount; j++) {
			// if all jobs before and on this day are finished,
			// we can go to the next day, even if there are usable machines left
			// we can determine that since the vector jobs is sorted
			if (jobs[reqNum].first > day) break;
			// if the current date is before the deadline for the job
			// we can add this job to the schedule and move to the next job
			// request
			if (jobs[reqNum].first + D >= day)
				schedule[day - 1].push_back(jobs[reqNum++].second);
			// otherwise, it is not feasible due to deadline
			else return mp(false, schedule);

			// if we have processed all the requests, we have found a feasible
			// sol
			if (reqNum == M) return mp(true, schedule);
		}
	}
	// if not all the requests can be processed within the given N days,
	// then it is not feasible
	return mp(false, schedule);
}

int main() {
	cin.tie(0)->sync_with_stdio(false);

	cin >> N >> D >> M;
	vector<pi> jobs(M);
	for (int i = 0; i < M; i++) {
		int day;
		cin >> day;
		// first: request date, second: index [1..M]
		jobs[i] = mp(day, i + 1);
	}
	// we sort the jobs by the request date in ascending order
	// sothat we can test them using isFeasible() in linear time whether they
	// can be done in given time using a certain amount of machines
	sort(all(jobs));

	vector<vi> result;
	// binary search on the number of machines for the minimum possible solution
	// left and right bound, l and r
	int l = 1, r = M;
	while (l < r) {
		int machineNum = (l + r) / 2;
		// test if the jobs would finish within the deadline
		// using the current # of machines, machineNum
		pair<bool, vector<vi>> curResult = isFeasible(jobs, machineNum);
		// if it's possible, we set the right bound as the tested machine number
		// and save the current schedule
		if (curResult.first) {
			r = machineNum;
			result = curResult.second;
		}
		// otherwise, we set the left bound to be the tested number + 1
		// and test the next machineNum again
		else
			l = machineNum + 1;
	}

	cout << l << "\n";
	for (int i = 0; i < N; i++) {
		for (int &idx : result[i]) cout << idx << " ";
		cout << 0 << "\n";
	}
}
# Verdict Execution time Memory Grader output
1 Correct 30 ms 3464 KB Output is correct
2 Correct 31 ms 3316 KB Output is correct
3 Correct 29 ms 3176 KB Output is correct
4 Correct 29 ms 3200 KB Output is correct
5 Correct 32 ms 3208 KB Output is correct
6 Correct 31 ms 3464 KB Output is correct
7 Correct 32 ms 3208 KB Output is correct
8 Correct 28 ms 3208 KB Output is correct
9 Correct 75 ms 9792 KB Output is correct
10 Correct 84 ms 10048 KB Output is correct
11 Correct 28 ms 2876 KB Output is correct
12 Correct 57 ms 5080 KB Output is correct
13 Correct 84 ms 8540 KB Output is correct
14 Correct 136 ms 10944 KB Output is correct
15 Correct 148 ms 11120 KB Output is correct
16 Correct 187 ms 16176 KB Output is correct
17 Correct 231 ms 18724 KB Output is correct
18 Correct 236 ms 23172 KB Output is correct
19 Correct 302 ms 28628 KB Output is correct
20 Correct 227 ms 18956 KB Output is correct