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Submission #844008

# Submission time Handle Problem Language Result Execution time Memory
844008 2023-09-04T21:49:50 Z cryan Mecho (IOI09_mecho) C++17
86 / 100
 1000 ms 8696 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("Ofast,unroll-loops")
#pragma GCC target("avx2,popcnt,lzcnt,abm,bmi,bmi2,fma,tune=native")
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<pair<pi, int>> 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().f;
		int dist = bfs.front().s;
		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] == 0 && dist_bees[new_i][new_j] > dist + 1) {
					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().f;
		int dist = bfs.front().s;
		bfs.pop();
		if (mecho_dist[i][j] > dist_bees[i][j] - (dist) / S)
			continue;
		int elapsed = (dist + 1) / S;
		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;

			// 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
86.0 / 100.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 4696 KB Output is correct
2 Correct 1 ms 4700 KB Output is correct
3 Correct 1 ms 4696 KB Output is correct
4 Correct 1 ms 4696 KB Output is correct
5 Correct 1 ms 4696 KB Output is correct
6 Correct 1 ms 4700 KB Output is correct
7 Correct 55 ms 8024 KB Output is correct
8 Correct 1 ms 4696 KB Output is correct
9 Correct 1 ms 4696 KB Output is correct
10 Correct 1 ms 4696 KB Output is correct
11 Correct 1 ms 4696 KB Output is correct
12 Correct 1 ms 4696 KB Output is correct
13 Correct 1 ms 4696 KB Output is correct
14 Correct 1 ms 4696 KB Output is correct
15 Correct 1 ms 4696 KB Output is correct
16 Correct 1 ms 4696 KB Output is correct
17 Correct 1 ms 4696 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 4696 KB Output is correct
21 Correct 1 ms 4696 KB Output is correct
22 Correct 1 ms 4696 KB Output is correct
23 Correct 1 ms 4696 KB Output is correct
24 Correct 1 ms 4696 KB Output is correct
25 Correct 1 ms 4696 KB Output is correct
26 Correct 1 ms 4696 KB Output is correct
27 Correct 1 ms 4704 KB Output is correct
28 Correct 1 ms 4700 KB Output is correct
29 Correct 1 ms 4696 KB Output is correct
30 Correct 1 ms 4696 KB Output is correct
31 Correct 1 ms 4696 KB Output is correct
32 Correct 1 ms 4700 KB Output is correct
33 Correct 4 ms 5208 KB Output is correct
34 Correct 5 ms 5208 KB Output is correct
35 Correct 253 ms 5324 KB Output is correct
36 Correct 5 ms 5208 KB Output is correct
37 Correct 8 ms 5208 KB Output is correct
38 Correct 372 ms 5456 KB Output is correct
39 Correct 7 ms 5720 KB Output is correct
40 Correct 8 ms 5464 KB Output is correct
41 Correct 528 ms 5896 KB Output is correct
42 Correct 8 ms 5976 KB Output is correct
43 Correct 10 ms 5724 KB Output is correct
44 Correct 730 ms 5988 KB Output is correct
45 Correct 9 ms 5720 KB Output is correct
46 Correct 12 ms 5724 KB Output is correct
47 Correct 967 ms 6264 KB Output is correct
48 Correct 11 ms 6232 KB Output is correct
49 Correct 15 ms 6236 KB Output is correct
50 Execution timed out 1060 ms 6640 KB Time limit exceeded
51 Correct 15 ms 6488 KB Output is correct
52 Correct 16 ms 6488 KB Output is correct
53 Execution timed out 1050 ms 7288 KB Time limit exceeded
54 Correct 16 ms 7000 KB Output is correct
55 Correct 20 ms 7000 KB Output is correct
56 Execution timed out 1031 ms 7508 KB Time limit exceeded
57 Correct 17 ms 7512 KB Output is correct
58 Correct 23 ms 7512 KB Output is correct
59 Execution timed out 1063 ms 8136 KB Time limit exceeded
60 Correct 19 ms 8024 KB Output is correct
61 Correct 30 ms 8024 KB Output is correct
62 Execution timed out 1042 ms 8696 KB Time limit exceeded
63 Correct 42 ms 8016 KB Output is correct
64 Correct 48 ms 8180 KB Output is correct
65 Correct 48 ms 8024 KB Output is correct
66 Correct 43 ms 8024 KB Output is correct
67 Correct 35 ms 8016 KB Output is correct
68 Correct 31 ms 8016 KB Output is correct
69 Correct 33 ms 8016 KB Output is correct
70 Correct 29 ms 8024 KB Output is correct
71 Correct 30 ms 8024 KB Output is correct
72 Correct 32 ms 8016 KB Output is correct
73 Correct 32 ms 8028 KB Output is correct
74 Correct 83 ms 8024 KB Output is correct
75 Correct 34 ms 8024 KB Output is correct
76 Correct 34 ms 8028 KB Output is correct
77 Correct 34 ms 8024 KB Output is correct
78 Correct 37 ms 8064 KB Output is correct
79 Correct 479 ms 8272 KB Output is correct
80 Correct 66 ms 8024 KB Output is correct
81 Correct 40 ms 8084 KB Output is correct
82 Correct 137 ms 8348 KB Output is correct
83 Correct 42 ms 8016 KB Output is correct
84 Correct 133 ms 8328 KB Output is correct
85 Correct 236 ms 8128 KB Output is correct
86 Correct 317 ms 8272 KB Output is correct
87 Correct 70 ms 8016 KB Output is correct
88 Correct 171 ms 8024 KB Output is correct
89 Correct 622 ms 8316 KB Output is correct
90 Correct 49 ms 8036 KB Output is correct
91 Correct 82 ms 8052 KB Output is correct
92 Correct 49 ms 8064 KB Output is correct