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Submission #844004

# Submission time Handle Problem Language Result Execution time Memory
844004 2023-09-04T21:41:59 Z cryan Mecho (IOI09_mecho) C++17
91 / 100
 1000 ms 8788 KB 
// oh, these hills, they burn so bright / oh, these hills, they bring me life
#include "bits/stdc++.h"
using namespace std;

using ll = long long;
#define all(x) begin(x), end(x)
#define rall(x) x.rbegin(), x.rend()
#define sz(x) (int)(x.size())
#define inf 1000000010
#define linf 0x3f3f3f3f3f3f3f3f
#define mp make_pair
#define f first
#define s second
#define pi pair<int, int>
#ifdef LOCAL
#include "/mnt/c/yukon/pp.hpp"
#else
#define endl '\n'
#endif

#pragma GCC optimize("O2,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
struct Event {
	pi loc;
	int dist;
};
int grid[801][801], dist_bees[801][801];
const int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};
int main() {
	cin.tie(0)->sync_with_stdio(0);

	int n;
	cin >> n;

	int S;
	cin >> S;

	vector<pi> hives;
	pi start, end;

	for (int i = 0; i < n; i++) {
		string st;
		cin >> st;

		for (int j = 0; j < n; j++) {
			if (st[j] == 'T')
				grid[i][j] = -1;
			else if (st[j] != 'D')
				grid[i][j] = 0;
			else
				grid[i][j] = 1, end = {i, j};

			if (st[j] == 'H') {
				hives.emplace_back(i, j);
			} else if (st[j] == 'M')
				start = {i, j};
		}
	}

	// let's get distance from bees first
	queue<Event> bfs;
	memset(dist_bees, 0x3f, sizeof dist_bees);

	for (auto &[i, j] : hives) {
		bfs.push({{i, j}, 0});
		dist_bees[i][j] = 0;
	}
	while (!bfs.empty()) {
		auto [i, j] = bfs.front().loc;
		int dist = bfs.front().dist;
		bfs.pop();

		if (dist_bees[i][j] < dist)
			continue;

		for (int d = 0; d < 4; d++) {
			int new_i = i + dx[d], new_j = j + dy[d];

			if (new_i >= 0 && new_i < n && new_j >= 0 && new_j < n) {
				if (grid[new_i][new_j] != -1 && dist_bees[new_i][new_j] > dist + 1 && pi{new_i, new_j} != end) {
					dist_bees[new_i][new_j] = dist + 1;
					bfs.push({{new_i, new_j}, dist + 1});
				}
			}
		}
	}
	// for (int i = 0; i < n; i++) {
	// 	cout << dist_bees[i] << endl;
	// }

	// now mecho's turn
	bfs.push({{start.f, start.s}, 0});
	// just store distance w/o S factor
	vector<vector<int>> mecho_dist(n, vector<int>(n, -inf));
	mecho_dist[start.f][start.s] = dist_bees[start.f][start.s];

	while (sz(bfs)) {
		auto [i, j] = bfs.front().loc;
		int dist = bfs.front().dist;
		bfs.pop();
		if (mecho_dist[i][j] > dist_bees[i][j] - (dist) / S)
			continue;
		for (int d = 0; d < 4; d++) {
			int ni = i + dx[d], nj = j + dy[d];

			if (ni < 0 || ni >= n || nj < 0 || nj >= n)
				continue;

			int elapsed = (dist + 1) / S;
			// if (ni == 3 && nj == 3) {
			// 	cout << dist + 1 << ' ' << elapsed << ' ' << dist_bees[ni][nj] << endl;
			// }
			int lead = min(mecho_dist[i][j], dist_bees[ni][nj] - elapsed);
			if (grid[ni][nj] != -1 && mecho_dist[ni][nj] < lead && elapsed < dist_bees[ni][nj]) {
				mecho_dist[ni][nj] = lead;
				bfs.push({{ni, nj}, dist + 1});
			}
		}
	}
	// cout << "________" << endl;
	// for (int i = 0; i < n; i++) {
	// 	cout << mecho_dist[i] << endl;
	// }
	// cout << "________" << endl;
	// for (int i = 0; i < n; i++) {
	// 	cout << mecho_lead[i] << endl;
	// }

	int ans = -inf;
	for (int d = 0; d < 4; d++) {
		int ni = end.f + dx[d], nj = end.s + dy[d];

		if (ni < 0 || ni >= n || nj < 0 || nj >= n)
			continue;
		if (grid[ni][nj] == -1 || mecho_dist[ni][nj] == inf)
			continue;

		ans = max(ans, mecho_dist[ni][nj] - 1);
		// int elapsed = (mecho_dist[ni][nj] + S) / S;
		// ans = max(ans, dist_bees[ni][nj] - elapsed);
	}
	if (ans < 0) {
		cout << -1 << endl;
	} else {
		cout << ans << endl;
	}
}

// don't get stuck on one approach
// question bounds
// flesh out your approach before implementing o.o
// math it out
// ok well X is always possible, how about X + 1 (etc.)

Subtask #1
91.0 / 100.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 4700 KB Output is correct
2 Correct 1 ms 4700 KB Output is correct
3 Correct 1 ms 4700 KB Output is correct
4 Correct 1 ms 4700 KB Output is correct
5 Correct 1 ms 4700 KB Output is correct
6 Correct 1 ms 4700 KB Output is correct
7 Correct 41 ms 8024 KB Output is correct
8 Correct 1 ms 4700 KB Output is correct
9 Correct 1 ms 4700 KB Output is correct
10 Correct 1 ms 4700 KB Output is correct
11 Correct 1 ms 4700 KB Output is correct
12 Correct 1 ms 4696 KB Output is correct
13 Correct 1 ms 4700 KB Output is correct
14 Correct 1 ms 4712 KB Output is correct
15 Correct 1 ms 4700 KB Output is correct
16 Correct 1 ms 4700 KB Output is correct
17 Correct 1 ms 4700 KB Output is correct
18 Correct 1 ms 4696 KB Output is correct
19 Correct 1 ms 4700 KB Output is correct
20 Correct 1 ms 4700 KB Output is correct
21 Correct 1 ms 4700 KB Output is correct
22 Correct 1 ms 4700 KB Output is correct
23 Correct 1 ms 4700 KB Output is correct
24 Correct 1 ms 4700 KB Output is correct
25 Correct 1 ms 4700 KB Output is correct
26 Correct 1 ms 4700 KB Output is correct
27 Correct 1 ms 4700 KB Output is correct
28 Correct 1 ms 4560 KB Output is correct
29 Correct 1 ms 4700 KB Output is correct
30 Correct 1 ms 4700 KB Output is correct
31 Correct 1 ms 4700 KB Output is correct
32 Correct 1 ms 4700 KB Output is correct
33 Correct 3 ms 5212 KB Output is correct
34 Correct 4 ms 5208 KB Output is correct
35 Correct 139 ms 5336 KB Output is correct
36 Correct 4 ms 5212 KB Output is correct
37 Correct 5 ms 5332 KB Output is correct
38 Correct 207 ms 5456 KB Output is correct
39 Correct 5 ms 5464 KB Output is correct
40 Correct 6 ms 5468 KB Output is correct
41 Correct 297 ms 5752 KB Output is correct
42 Correct 6 ms 5720 KB Output is correct
43 Correct 7 ms 5720 KB Output is correct
44 Correct 411 ms 5972 KB Output is correct
45 Correct 7 ms 5724 KB Output is correct
46 Correct 8 ms 5724 KB Output is correct
47 Correct 542 ms 6652 KB Output is correct
48 Correct 8 ms 6236 KB Output is correct
49 Correct 10 ms 6308 KB Output is correct
50 Correct 698 ms 6672 KB Output is correct
51 Correct 11 ms 6492 KB Output is correct
52 Correct 12 ms 6492 KB Output is correct
53 Correct 914 ms 7248 KB Output is correct
54 Correct 11 ms 7000 KB Output is correct
55 Correct 14 ms 7136 KB Output is correct
56 Execution timed out 1092 ms 7584 KB Time limit exceeded
57 Correct 14 ms 7680 KB Output is correct
58 Correct 15 ms 7516 KB Output is correct
59 Execution timed out 1096 ms 8136 KB Time limit exceeded
60 Correct 14 ms 8024 KB Output is correct
61 Correct 17 ms 8028 KB Output is correct
62 Execution timed out 1020 ms 8788 KB Time limit exceeded
63 Correct 32 ms 7820 KB Output is correct
64 Correct 36 ms 8028 KB Output is correct
65 Correct 34 ms 8028 KB Output is correct
66 Correct 37 ms 8028 KB Output is correct
67 Correct 27 ms 8024 KB Output is correct
68 Correct 25 ms 8020 KB Output is correct
69 Correct 26 ms 7860 KB Output is correct
70 Correct 23 ms 8028 KB Output is correct
71 Correct 24 ms 7860 KB Output is correct
72 Correct 27 ms 7856 KB Output is correct
73 Correct 23 ms 8028 KB Output is correct
74 Correct 51 ms 8028 KB Output is correct
75 Correct 23 ms 8028 KB Output is correct
76 Correct 24 ms 8104 KB Output is correct
77 Correct 24 ms 8028 KB Output is correct
78 Correct 24 ms 8028 KB Output is correct
79 Correct 293 ms 8224 KB Output is correct
80 Correct 42 ms 8084 KB Output is correct
81 Correct 26 ms 8024 KB Output is correct
82 Correct 84 ms 8356 KB Output is correct
83 Correct 28 ms 8028 KB Output is correct
84 Correct 73 ms 8084 KB Output is correct
85 Correct 142 ms 8024 KB Output is correct
86 Correct 182 ms 8240 KB Output is correct
87 Correct 44 ms 8028 KB Output is correct
88 Correct 103 ms 8024 KB Output is correct
89 Correct 348 ms 8224 KB Output is correct
90 Correct 32 ms 8028 KB Output is correct
91 Correct 49 ms 8028 KB Output is correct
92 Correct 32 ms 8024 KB Output is correct