Submission #747806

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
747806	2023-05-24T19:14:47 Z	AverageAmogusEnjoyer	Mecho (IOI09_mecho)	C++17	100 / 100	160 ms	6392 KB

mecho

// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template <class T>
using indexed_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define all(x) x.begin(), x.end() 
#define sz(x) (int) x.size()
#define pb push_back
#define ll long long
#define nl '\n'

/*

Mecho can only walk on grass and cannot go through trees or hives, and he can make at most S steps per minute.
every minute
he eats or 
he leaves immediately and takes up to S steps through the forest as described above

bees spread to grassy cells

trees = no one can go there

m = mecho, grassy cells => i will replace with g

g = grassy

d = mecho home; bees cannot go / pass here

h = hive

*/

const int N = 810;

char grid[N][N];
int stepsMecho[N][N], stepsBee[N][N];
int n, s;
array<int, 2> Mecho, MechoHouse;
vector<array<int, 2>> Bee;
vector<array<int,2>> moves = {{-1,0},{1,0},{0,-1},{0,1}};

struct m{
	bool isMecho;
	int x,y;
};

bool good(int x, int y) {
	return 0 <= x && x < n && 0 <= y && y < n && grid[x][y] != 'T';
}

bool isHome(int x, int y) {
	return x == MechoHouse[0] && y == MechoHouse[1];
}

void debug() {
	cout << "Mecho: " << nl;
	for (int i=0;i<n;i++) {
		for (int j=0;j<n;j++) {
			cout << stepsMecho[i][j] << " ";
		}
		cout << nl;
	}
	cout << "Bees: " << nl;
	for (int i=0;i<n;i++) {
		for (int j=0;j<n;j++) {
			cout << stepsBee[i][j] << " ";
		}
		cout << nl;
	}
}
/*
bool bs(int steps) {
	memset(stepsMecho,-1,sizeof(stepsMecho));
	memset(stepsBee,-1,sizeof(stepsBee));
	queue<m> q, q2;
	q2.push(m{true,Mecho[0],Mecho[1]});
	stepsMecho[Mecho[0]][Mecho[1]] = 0;
	for (auto [x,y]:Bee) {
		q.push(m{false,x,y});
		stepsBee[x][y]=0;
	}
	while(!q.empty()) {
		m v = q.front(); q.pop();
		if (stepsBee[v.x][v.y] == steps) { q2.push(v); continue; }
 		for (auto [addx,addy]: moves) {
			int nx = v.x + addx, ny = v.y + addy;
			if (good(nx,ny) && !isHome(nx,ny) && stepsBee[nx][ny] == -1) {
				q.push(m{false,nx,ny});
				stepsBee[nx][ny] = stepsBee[v.x][v.y]+1;
			}
		}
	}
	for (int i=0;i<n;i++)
		for (int j=0;j<n;j++)
			if (stepsBee[i][j] != -1)
				stepsBee[i][j] = 0;
	while(!q2.empty()) {
		m v = q2.front(); q2.pop();
		// if (steps==1) {
		// 	cout << v.isMecho << " " << v.x << " " << v.y << nl;
		// 	debug();
		// 	cout << nl;
		// }
		if (v.isMecho) {
			if (stepsBee[v.x][v.y] != -1 && stepsBee[v.x][v.y] <= (stepsMecho[v.x][v.y]+s-1)/s) { continue; }
			for (auto [addx,addy]: moves) {
				int nx = v.x + addx, ny = v.y + addy;
				if (good(nx,ny) && stepsMecho[nx][ny] == -1 && (stepsBee[nx][ny] == -1 || stepsBee[nx][ny] > (stepsMecho[v.x][v.y]+s)/s)) {
					if (isHome(nx,ny)) { return 1; }
					stepsMecho[nx][ny] = stepsMecho[v.x][v.y]+1;
					q2.push(m{true,nx,ny});
				}
			}
		} else {
			for (auto [addx,addy]: moves) {
				int nx = v.x + addx, ny = v.y + addy;
				if (good(nx,ny) && !isHome(nx,ny) && stepsBee[nx][ny] == -1) {
					q2.push(m{false,nx,ny});
					stepsBee[nx][ny] = stepsBee[v.x][v.y]+1;
				}
			}
		}
	}
	return 0;
}
*/

void reset() {
	memset(stepsMecho,-1,sizeof(stepsMecho));
}

bool bs(int steps) {
	if (stepsBee[Mecho[0]][Mecho[1]] != -1 && stepsBee[Mecho[0]][Mecho[1]] <= steps) return 0;
	reset();
	queue<array<int,2>> q;
	q.push(Mecho);
	stepsMecho[Mecho[0]][Mecho[1]] = 0;
	while(!q.empty()) {
		auto [x,y] = q.front(); q.pop();
		for (auto [px,py]:moves) {
			int nx = x + px, ny = y + py;
			if (good(nx,ny) && stepsMecho[nx][ny] == -1 && (stepsMecho[x][y] + 1) / s < (stepsBee[nx][ny] - steps)) {
				stepsMecho[nx][ny] = stepsMecho[x][y]+1;
				q.push({nx,ny});
			}
		}
	}
	for (auto [px,py]:moves) {
		int nx = MechoHouse[0] + px, ny = MechoHouse[1] + py;
		if (good(nx,ny) && stepsMecho[nx][ny] != -1) return 1;
	}
	return 0;
}

signed main() {
	// freopen(".in", "r", stdin);
	// freopen(".out", "w", stdout);
	ios_base::sync_with_stdio(0); cin.tie(0);
	memset(stepsBee,-1,sizeof(stepsBee));	
	cin >> n >> s;
	for (int i=0;i<n;i++)
		for (int j=0;j<n;j++) {
			cin >> grid[i][j];
			if (grid[i][j]=='M') {
				grid[i][j] = 'G';
				Mecho = {i,j};
			}
			if (grid[i][j]=='H') {
				Bee.pb({i,j});
			}
			if (grid[i][j]=='D') {
				MechoHouse = {i,j};
			}
		}
	queue<array<int,2>> q;
	for (auto [x,y]:Bee) {
		q.push({x,y});
		stepsBee[x][y] = 0;
	}
	while(!q.empty()) {
		auto [x,y] = q.front(); q.pop();
		for (auto [px,py]:moves) {
			int nx = x + px, ny = y + py;
			if (good(nx,ny) && stepsBee[nx][ny] == -1 && !isHome(nx,ny)) {
				stepsBee[nx][ny] = stepsBee[x][y]+1;
				q.push({nx,ny});
			}
		}
	}
	int lo = 0, hi = 1e9;
	while(lo<=hi) {
		int mid = (lo+hi)/2;
		if (bs(mid)) {
			lo = mid + 1;
		} else {
			hi = mid - 1;
		}
	}
	cout << lo-1;
}

Subtask #1

100.0 / 100.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	2 ms	5332 KB	Output is correct
2	Correct	3 ms	5460 KB	Output is correct
3	Correct	3 ms	5460 KB	Output is correct
4	Correct	2 ms	5460 KB	Output is correct
5	Correct	2 ms	5460 KB	Output is correct
6	Correct	2 ms	5460 KB	Output is correct
7	Correct	73 ms	6100 KB	Output is correct
8	Correct	3 ms	5460 KB	Output is correct
9	Correct	3 ms	5460 KB	Output is correct
10	Correct	3 ms	5460 KB	Output is correct
11	Correct	3 ms	5460 KB	Output is correct
12	Correct	3 ms	5460 KB	Output is correct
13	Correct	3 ms	5460 KB	Output is correct
14	Correct	3 ms	5460 KB	Output is correct
15	Correct	3 ms	5460 KB	Output is correct
16	Correct	2 ms	5460 KB	Output is correct
17	Correct	3 ms	5460 KB	Output is correct
18	Correct	2 ms	5460 KB	Output is correct
19	Correct	4 ms	5460 KB	Output is correct
20	Correct	3 ms	5460 KB	Output is correct
21	Correct	3 ms	5460 KB	Output is correct
22	Correct	2 ms	5460 KB	Output is correct
23	Correct	3 ms	5460 KB	Output is correct
24	Correct	3 ms	5460 KB	Output is correct
25	Correct	3 ms	5460 KB	Output is correct
26	Correct	3 ms	5460 KB	Output is correct
27	Correct	3 ms	5460 KB	Output is correct
28	Correct	3 ms	5460 KB	Output is correct
29	Correct	3 ms	5460 KB	Output is correct
30	Correct	3 ms	5460 KB	Output is correct
31	Correct	3 ms	5460 KB	Output is correct
32	Correct	3 ms	5460 KB	Output is correct
33	Correct	7 ms	5716 KB	Output is correct
34	Correct	6 ms	5716 KB	Output is correct
35	Correct	22 ms	5736 KB	Output is correct
36	Correct	6 ms	5716 KB	Output is correct
37	Correct	7 ms	5776 KB	Output is correct
38	Correct	23 ms	5704 KB	Output is correct
39	Correct	9 ms	5812 KB	Output is correct
40	Correct	8 ms	5696 KB	Output is correct
41	Correct	29 ms	5716 KB	Output is correct
42	Correct	8 ms	5856 KB	Output is correct
43	Correct	8 ms	5844 KB	Output is correct
44	Correct	40 ms	5844 KB	Output is correct
45	Correct	10 ms	5844 KB	Output is correct
46	Correct	9 ms	5844 KB	Output is correct
47	Correct	44 ms	5888 KB	Output is correct
48	Correct	12 ms	5844 KB	Output is correct
49	Correct	13 ms	5940 KB	Output is correct
50	Correct	60 ms	5924 KB	Output is correct
51	Correct	14 ms	5972 KB	Output is correct
52	Correct	14 ms	5972 KB	Output is correct
53	Correct	68 ms	5960 KB	Output is correct
54	Correct	16 ms	6016 KB	Output is correct
55	Correct	19 ms	6000 KB	Output is correct
56	Correct	70 ms	5896 KB	Output is correct
57	Correct	16 ms	6056 KB	Output is correct
58	Correct	14 ms	5972 KB	Output is correct
59	Correct	90 ms	6048 KB	Output is correct
60	Correct	17 ms	5972 KB	Output is correct
61	Correct	18 ms	6080 KB	Output is correct
62	Correct	99 ms	6024 KB	Output is correct
63	Correct	96 ms	6084 KB	Output is correct
64	Correct	160 ms	6084 KB	Output is correct
65	Correct	153 ms	6100 KB	Output is correct
66	Correct	108 ms	6100 KB	Output is correct
67	Correct	99 ms	5960 KB	Output is correct
68	Correct	44 ms	6004 KB	Output is correct
69	Correct	48 ms	6112 KB	Output is correct
70	Correct	32 ms	6224 KB	Output is correct
71	Correct	33 ms	6008 KB	Output is correct
72	Correct	31 ms	6008 KB	Output is correct
73	Correct	32 ms	6348 KB	Output is correct
74	Correct	49 ms	6368 KB	Output is correct
75	Correct	53 ms	6384 KB	Output is correct
76	Correct	50 ms	6276 KB	Output is correct
77	Correct	52 ms	6392 KB	Output is correct
78	Correct	66 ms	6360 KB	Output is correct
79	Correct	46 ms	6348 KB	Output is correct
80	Correct	54 ms	6364 KB	Output is correct
81	Correct	59 ms	6240 KB	Output is correct
82	Correct	49 ms	6260 KB	Output is correct
83	Correct	62 ms	6312 KB	Output is correct
84	Correct	57 ms	6196 KB	Output is correct
85	Correct	55 ms	6204 KB	Output is correct
86	Correct	65 ms	6324 KB	Output is correct
87	Correct	58 ms	6316 KB	Output is correct
88	Correct	64 ms	6348 KB	Output is correct
89	Correct	65 ms	6220 KB	Output is correct
90	Correct	68 ms	6148 KB	Output is correct
91	Correct	63 ms	6228 KB	Output is correct
92	Correct	74 ms	6144 KB	Output is correct