oj.uz

답안 #621486

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
621486 2022-08-03T21:09:42 Z abcisosm5 Mecho (IOI09_mecho) C++17
100 / 100
 310 ms 2036 KB 
#include <bits/stdc++.h>
using namespace std;
#define pi pair<int, int>
#define f first
#define s second

int N, S;
const int MN = 800;
char grid[MN][MN] = {{}};
vector<pi> hives;
pi M; pi D;
int dx[4] = {1, -1, 0, 0};
int dy[4] = {0, 0, 1, -1};

void movebees(queue<pair<pi,int>> (&b), char (&v)[MN][MN], int t){
	if(b.empty()) return; 
	int start = b.front().s;
	for(int i = 0; i < t; i++){
		while(!b.empty() && b.front().s <= start + i){
			pair<pi, int> x = b.front(); b.pop();
			pi p = x.f; int index = x.s;
			for(int d = 0; d < 4; d++){
				int nx = p.f + dx[d]; int ny = p.s + dy[d];
				if(nx < 0 || nx >= N || ny < 0 || ny >= N) continue;
				if(v[nx][ny] != 'B' && (grid[nx][ny] == 'G' || grid[nx][ny] == 'M')){
					v[nx][ny] = 'B';
					b.push({{nx, ny}, index+1});
				}
			}
		}
	}
}

bool movemecho(queue<pair<pi, int>> (&m), char (&v)[MN][MN]){
	if(m.empty()) return false; 
	int start = m.front().s;
	for(int i = 0; i < S; i++){
		while(!m.empty() && m.front().s <= start + i){
			pair<pi, int> x = m.front(); m.pop();
			pi p = x.f; int index = x.s;
			if(v[p.f][p.s] == 'B') continue; //invalidate positions that are now occupied by bees
			for(int d = 0; d < 4; d++){
				int nx = p.f + dx[d]; int ny = p.s + dy[d];
				if(nx < 0 || nx >= N || ny < 0 || ny >= N) continue;
				if(!v[nx][ny] && grid[nx][ny] != 'T'){
					v[nx][ny] = 'M';
					if(grid[nx][ny] == 'D') return true;
					m.push({{nx, ny}, index+1});
				}
			}
		}
	}
	return false;
}

bool works(int t){ //O(N^2)
	char visited[MN][MN] = {{}};
	queue<pair<pi, int>> mecho; mecho.push({M,0}); visited[M.f][M.s] = 'M';
	queue<pair<pi, int>> bees;
	for(pi p : hives){
		bees.push({p,0});
		visited[p.first][p.second] = 'B'; 
	}
	movebees(bees, visited, t);
	
	for(int i = 0; i < N*N/2; i++){
		//first, move mecho S steps
		if(mecho.empty()) break;
		bool success = movemecho(mecho, visited);
		if(success) return true;

		//then, move bees 1 step
		movebees(bees, visited, 1);
	}
	return false;
}

int main(){
	cin.tie(0)->sync_with_stdio(0);

	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') M = {i, j};
			if(grid[i][j] == 'D') D = {i, j};
			if(grid[i][j] == 'H') hives.push_back({i,j});
		}
	}


	int lo = -1; int hi = N*N/2; //amount of head start to bees

	while(lo < hi){ // in total, O(N^2 log N)
		int mid = lo + (hi - lo + 1) / 2;
		if(works(mid)){
			lo = mid;
		} else {
			hi = mid - 1;
		}
	}

	cout << lo;
}

Subtask #1
100.0 / 100.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 852 KB Output is correct
2 Correct 1 ms 852 KB Output is correct
3 Correct 1 ms 852 KB Output is correct
4 Correct 1 ms 852 KB Output is correct
5 Correct 1 ms 852 KB Output is correct
6 Correct 1 ms 852 KB Output is correct
7 Correct 236 ms 1724 KB Output is correct
8 Correct 1 ms 852 KB Output is correct
9 Correct 1 ms 852 KB Output is correct
10 Correct 2 ms 852 KB Output is correct
11 Correct 1 ms 852 KB Output is correct
12 Correct 1 ms 980 KB Output is correct
13 Correct 2 ms 1000 KB Output is correct
14 Correct 2 ms 980 KB Output is correct
15 Correct 1 ms 852 KB Output is correct
16 Correct 1 ms 852 KB Output is correct
17 Correct 1 ms 852 KB Output is correct
18 Correct 1 ms 852 KB Output is correct
19 Correct 1 ms 852 KB Output is correct
20 Correct 1 ms 852 KB Output is correct
21 Correct 1 ms 852 KB Output is correct
22 Correct 1 ms 980 KB Output is correct
23 Correct 1 ms 980 KB Output is correct
24 Correct 1 ms 980 KB Output is correct
25 Correct 1 ms 980 KB Output is correct
26 Correct 2 ms 980 KB Output is correct
27 Correct 1 ms 980 KB Output is correct
28 Correct 1 ms 980 KB Output is correct
29 Correct 2 ms 980 KB Output is correct
30 Correct 2 ms 980 KB Output is correct
31 Correct 2 ms 992 KB Output is correct
32 Correct 3 ms 980 KB Output is correct
33 Correct 22 ms 1220 KB Output is correct
34 Correct 19 ms 1108 KB Output is correct
35 Correct 33 ms 1108 KB Output is correct
36 Correct 27 ms 1252 KB Output is correct
37 Correct 30 ms 1268 KB Output is correct
38 Correct 46 ms 1236 KB Output is correct
39 Correct 38 ms 1236 KB Output is correct
40 Correct 34 ms 1284 KB Output is correct
41 Correct 59 ms 1236 KB Output is correct
42 Correct 46 ms 1328 KB Output is correct
43 Correct 46 ms 1316 KB Output is correct
44 Correct 78 ms 1324 KB Output is correct
45 Correct 65 ms 1360 KB Output is correct
46 Correct 70 ms 1376 KB Output is correct
47 Correct 99 ms 1384 KB Output is correct
48 Correct 76 ms 1396 KB Output is correct
49 Correct 72 ms 1396 KB Output is correct
50 Correct 106 ms 1408 KB Output is correct
51 Correct 85 ms 1436 KB Output is correct
52 Correct 81 ms 1428 KB Output is correct
53 Correct 139 ms 1452 KB Output is correct
54 Correct 116 ms 1492 KB Output is correct
55 Correct 87 ms 1492 KB Output is correct
56 Correct 183 ms 1504 KB Output is correct
57 Correct 105 ms 1516 KB Output is correct
58 Correct 99 ms 1492 KB Output is correct
59 Correct 143 ms 1540 KB Output is correct
60 Correct 118 ms 1488 KB Output is correct
61 Correct 109 ms 1612 KB Output is correct
62 Correct 166 ms 1580 KB Output is correct
63 Correct 239 ms 1556 KB Output is correct
64 Correct 269 ms 1580 KB Output is correct
65 Correct 244 ms 1560 KB Output is correct
66 Correct 269 ms 1564 KB Output is correct
67 Correct 248 ms 1564 KB Output is correct
68 Correct 255 ms 1596 KB Output is correct
69 Correct 225 ms 1612 KB Output is correct
70 Correct 249 ms 1620 KB Output is correct
71 Correct 272 ms 1620 KB Output is correct
72 Correct 303 ms 1604 KB Output is correct
73 Correct 196 ms 2016 KB Output is correct
74 Correct 253 ms 2004 KB Output is correct
75 Correct 289 ms 2004 KB Output is correct
76 Correct 306 ms 2004 KB Output is correct
77 Correct 257 ms 2004 KB Output is correct
78 Correct 259 ms 1948 KB Output is correct
79 Correct 266 ms 1948 KB Output is correct
80 Correct 263 ms 1948 KB Output is correct
81 Correct 263 ms 1944 KB Output is correct
82 Correct 271 ms 1960 KB Output is correct
83 Correct 269 ms 1888 KB Output is correct
84 Correct 294 ms 1888 KB Output is correct
85 Correct 284 ms 1908 KB Output is correct
86 Correct 270 ms 2036 KB Output is correct
87 Correct 310 ms 1880 KB Output is correct
88 Correct 256 ms 1804 KB Output is correct
89 Correct 262 ms 1804 KB Output is correct
90 Correct 256 ms 1808 KB Output is correct
91 Correct 257 ms 1816 KB Output is correct
92 Correct 261 ms 1812 KB Output is correct