Submission #751844

# Submission time Handle Problem Language Result Execution time Memory
751844 2023-06-01T15:35:39 Z ndh990 Job Scheduling (CEOI12_jobs) C++11
100 / 100
410 ms 26388 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 33 ms 3084 KB Output is correct
2 Correct 34 ms 2984 KB Output is correct
3 Correct 34 ms 3040 KB Output is correct
4 Correct 37 ms 3004 KB Output is correct
5 Correct 31 ms 2968 KB Output is correct
6 Correct 31 ms 2976 KB Output is correct
7 Correct 32 ms 2968 KB Output is correct
8 Correct 29 ms 2972 KB Output is correct
9 Correct 76 ms 9724 KB Output is correct
10 Correct 80 ms 9748 KB Output is correct
11 Correct 37 ms 2684 KB Output is correct
12 Correct 74 ms 4876 KB Output is correct
13 Correct 119 ms 8564 KB Output is correct
14 Correct 190 ms 10748 KB Output is correct
15 Correct 191 ms 10892 KB Output is correct
16 Correct 269 ms 16136 KB Output is correct
17 Correct 331 ms 18836 KB Output is correct
18 Correct 343 ms 23220 KB Output is correct
19 Correct 410 ms 26388 KB Output is correct
20 Correct 327 ms 18820 KB Output is correct