Submission #1037051

#	Time	Username	Problem	Language	Result	Execution time	Memory
1037051		sssamui	Mecho (IOI09_mecho)	C++17	0 / 100	137 ms	4188 KiB

mecho

#include <iostream>
#include <cstdio>
#include <vector>
#include <cmath>
#include <queue>
using namespace std;

vector<vector<char>> grd(802, vector<char>(802, 'T'));
vector<vector<bool>> swm(802, vector<bool>(802, false));
vector<vector<int>> btime(802, vector<int>(802, 0));
int sttr, sttc;
int dstr, dstc;
int h, s;

vector<int> radd = { -1, 0, 1, 0 };
vector<int> cadd = { 0, -1, 0, 1 };

bool check(int tchk)
{
	queue<pair<int, pair<int, int>>> bfs;
	bfs.push({ 0, {sttr, sttc} });
	vector<vector<bool>> poss(h + 2, vector<bool>(h + 2, false));
	poss[sttr][sttc] = true;
	while (!bfs.empty() && !poss[dstr][dstc])
	{
		int r = bfs.front().second.first, c = bfs.front().second.second, dst = bfs.front().first;
		bfs.pop();
		for (int dir = 0; dir < 4; dir++) if (!poss[r + radd[dir]][c + cadd[dir]]) if (grd[r + radd[dir]][c + cadd[dir]] == 'G')
			if ((dst + 1) / s < btime[r + radd[dir]][c + cadd[dir]] - tchk)
			{
				poss[r + radd[dir]][c + cadd[dir]] = true;
				bfs.push({ dst + 1, {r + radd[dir], c + cadd[dir]} });
			}
	}

	return poss[dstr][dstc];
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

	cin >> h >> s;
	queue<pair<int, int>> swmpcs;
	for (int i = 1; i <= h; i++) for (int j = 1; j <= h; j++)
	{
		cin >> grd[i][j];
		if (grd[i][j] == 'M')
		{
			sttr = i;
			sttc = j;
			grd[i][j] = 'G';
		}

		else if (grd[i][j] == 'D')
		{
			dstr = i;
			dstc = j;
			grd[i][j] = 'T';
		}

		else if (grd[i][j] == 'H')
		{
			swmpcs.push({ i, j });
			grd[i][j] = 'T';
		}
	}

	while (!swmpcs.empty())
	{
		int r = swmpcs.front().first, c = swmpcs.front().second;
		swmpcs.pop();
		for (int dir = 0; dir < 4; dir++) if ((!swm[r + radd[dir]][c + cadd[dir]]) && (grd[r + radd[dir]][c + cadd[dir]] == 'G'))
		{
			swm[r + radd[dir]][c + cadd[dir]] = true;
			btime[r + radd[dir]][c + cadd[dir]] = btime[r][c] + 1;
			swmpcs.push({ r + radd[dir], c + cadd[dir] });
		}
	}


	btime[dstr][dstc] = 2 * h;
	grd[dstr][dstc] = 'G';

	int l = -1, r = 3600;
	while (l < r)
	{
		int mid = (l + r + 1) / 2;
		if (check(mid)) l = mid;
		else r = mid - 1;
	}
}

• Subtask 1: 0 / 100