oj.uz

Submission #844015

# Submission time Handle Problem Language Result Execution time Memory
844015 2023-09-04T21:57:34 Z cryan Mecho (IOI09_mecho) C++17
94 / 100
 1000 ms 8616 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")
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] == 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().loc;
		int dist = bfs.front().dist;
		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] == 0 && 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
94.0 / 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 29 ms 7980 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 4700 KB Output is correct
13 Correct 1 ms 4556 KB Output is correct
14 Correct 1 ms 4700 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 4700 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 4564 KB Output is correct
22 Correct 1 ms 4728 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 4700 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 4696 KB Output is correct
32 Correct 1 ms 4700 KB Output is correct
33 Correct 3 ms 5212 KB Output is correct
34 Correct 3 ms 5076 KB Output is correct
35 Correct 105 ms 5336 KB Output is correct
36 Correct 3 ms 5212 KB Output is correct
37 Correct 4 ms 5212 KB Output is correct
38 Correct 158 ms 5712 KB Output is correct
39 Correct 4 ms 5468 KB Output is correct
40 Correct 4 ms 5468 KB Output is correct
41 Correct 224 ms 5656 KB Output is correct
42 Correct 4 ms 5724 KB Output is correct
43 Correct 5 ms 5752 KB Output is correct
44 Correct 319 ms 6228 KB Output is correct
45 Correct 7 ms 5724 KB Output is correct
46 Correct 6 ms 5724 KB Output is correct
47 Correct 405 ms 6248 KB Output is correct
48 Correct 6 ms 6236 KB Output is correct
49 Correct 7 ms 6236 KB Output is correct
50 Correct 535 ms 6768 KB Output is correct
51 Correct 7 ms 6492 KB Output is correct
52 Correct 9 ms 6492 KB Output is correct
53 Correct 709 ms 7140 KB Output is correct
54 Correct 8 ms 7004 KB Output is correct
55 Correct 10 ms 7004 KB Output is correct
56 Correct 860 ms 8024 KB Output is correct
57 Correct 11 ms 7512 KB Output is correct
58 Correct 11 ms 7396 KB Output is correct
59 Execution timed out 1054 ms 8504 KB Time limit exceeded
60 Correct 10 ms 8040 KB Output is correct
61 Correct 14 ms 8028 KB Output is correct
62 Execution timed out 1093 ms 8616 KB Time limit exceeded
63 Correct 27 ms 8028 KB Output is correct
64 Correct 30 ms 8028 KB Output is correct
65 Correct 30 ms 8028 KB Output is correct
66 Correct 27 ms 8028 KB Output is correct
67 Correct 23 ms 7812 KB Output is correct
68 Correct 22 ms 8028 KB Output is correct
69 Correct 26 ms 8028 KB Output is correct
70 Correct 28 ms 7856 KB Output is correct
71 Correct 20 ms 8028 KB Output is correct
72 Correct 23 ms 8028 KB Output is correct
73 Correct 18 ms 8028 KB Output is correct
74 Correct 42 ms 8080 KB Output is correct
75 Correct 18 ms 8028 KB Output is correct
76 Correct 20 ms 7908 KB Output is correct
77 Correct 20 ms 8028 KB Output is correct
78 Correct 20 ms 7928 KB Output is correct
79 Correct 220 ms 8532 KB Output is correct
80 Correct 32 ms 8028 KB Output is correct
81 Correct 20 ms 8028 KB Output is correct
82 Correct 63 ms 8140 KB Output is correct
83 Correct 22 ms 7880 KB Output is correct
84 Correct 75 ms 8028 KB Output is correct
85 Correct 103 ms 8088 KB Output is correct
86 Correct 135 ms 8124 KB Output is correct
87 Correct 35 ms 8028 KB Output is correct
88 Correct 76 ms 8172 KB Output is correct
89 Correct 258 ms 8316 KB Output is correct
90 Correct 28 ms 8024 KB Output is correct
91 Correct 39 ms 8028 KB Output is correct
92 Correct 26 ms 8028 KB Output is correct