Submission #1002839

#	Time	Username	Problem	Language	Result	Execution time	Memory
1002839		Tob	Mecho (IOI09_mecho)	C++14	100 / 100	90 ms	7496 KiB

mecho

#include <bits/stdc++.h>

#define ll long long
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define pb push_back
#define FIO ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0)

using namespace std;

typedef pair <ll, ll> pii;

const int N = 807, inf = 1e9;
int dx[] = {0, 1, 0, -1};
int dy[] = {1, 0, -1, 0};

int n, S, stx, sty, enx, eny;
char mat[N][N];
int bee[N][N], bio[N][N];

int main () {
	FIO;
	cin >> n >> S;
	
	vector <pii> v;
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= n; j++) {
			cin >> mat[i][j];
			if (mat[i][j] == 'M') stx = i, sty = j;
			if (mat[i][j] == 'D') enx = i, eny = j;
			if (mat[i][j] == 'H') v.pb({i, j});
		}
	}
	for (int i = 1; i <= n; i++) for (int j = 1; j <= n; j++) bee[i][j] = inf;
	for (int i = 0; i <= n+1; i++) bee[i][0] = bee[i][n+1] = bee[0][i] = bee[n+1][i] = -1;
	queue <pii> q;
	for (auto it : v) {
		q.push(it);
		bee[it.F][it.S] = 0;
	}
	while (!q.empty()) {
		pii fr = q.front(); q.pop();
		int x = fr.F, y = fr.S;
		for (int i = 0; i < 4; i++) {
			int nx = x + dx[i], ny = y + dy[i];
			if (bee[nx][ny] != inf) continue;
			if (mat[nx][ny] == 'T' || mat[nx][ny] == 'D') continue;
			bee[nx][ny] = bee[x][y] + 1;
			q.push({nx, ny});
		}
	}
	
	int lo = -1, hi = 1e8;
	while (!q.empty()) q.pop();
	while (lo < hi) {
		int mid = (lo + hi + 1) / 2;
		if (mid >= bee[stx][sty]) {
			hi = mid-1;
			continue;
		}
		memset(bio, -1, sizeof bio);
		for (int i = 0; i <= n+1; i++) bio[i][0] = bio[i][n+1] = bio[0][i] = bio[n+1][i] = -2;
		bio[stx][sty] = 0;
		q.push({stx, sty});
		while (!q.empty()) {
			pii fr = q.front(); q.pop();
			int x = fr.F, y = fr.S;
			int d = bio[x][y];
			for (int i = 0; i < 4; i++) {
				int nx = x + dx[i], ny = y + dy[i];
				if (bio[nx][ny] != -1) continue;
				if (mat[nx][ny] == 'T' || bee[nx][ny] <= mid+(d+1)/S) continue;
				bio[nx][ny] = d + 1;
				q.push({nx, ny});
			}
		}
		if (bio[enx][eny] == -1) hi = mid-1;
		else lo = mid;
	}
	cout << lo << "\n";

	return 0;
}

• Subtask 1: 100 / 100