Submission #774381

# Submission time Handle Problem Language Result Execution time Memory
774381 2023-07-05T16:52:58 Z RonTheprogrammer Job Scheduling (CEOI12_jobs) C++17
100 / 100
330 ms 26416 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 22 ms 2968 KB Output is correct
2 Correct 26 ms 2972 KB Output is correct
3 Correct 22 ms 3084 KB Output is correct
4 Correct 22 ms 3084 KB Output is correct
5 Correct 22 ms 2976 KB Output is correct
6 Correct 26 ms 3100 KB Output is correct
7 Correct 23 ms 3084 KB Output is correct
8 Correct 23 ms 3084 KB Output is correct
9 Correct 56 ms 9648 KB Output is correct
10 Correct 62 ms 9708 KB Output is correct
11 Correct 36 ms 2752 KB Output is correct
12 Correct 59 ms 4864 KB Output is correct
13 Correct 81 ms 8512 KB Output is correct
14 Correct 138 ms 10788 KB Output is correct
15 Correct 145 ms 10888 KB Output is correct
16 Correct 198 ms 16040 KB Output is correct
17 Correct 249 ms 18728 KB Output is correct
18 Correct 250 ms 23200 KB Output is correct
19 Correct 330 ms 26416 KB Output is correct
20 Correct 259 ms 18756 KB Output is correct