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Submission #907251

# Submission time Handle Problem Language Result Execution time Memory
907251 2024-01-15T10:19:36 Z Ghetto Mecho (IOI09_mecho) C++17
100 / 100
 300 ms 7768 KB 
#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
const int MAX_N = 800 + 5, INF = 1e9, MAX_T = MAX_N * MAX_N;

int n, s;
char arr[MAX_N][MAX_N];

bool bee_seen[MAX_N][MAX_N];
int bee_dist[MAX_N][MAX_N]; // INF if unreachable
queue<pii> bee_order;
void bee_bfs() {
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++)
            if (arr[i][j] == 'H') {
                bee_seen[i][j] = true;
                bee_order.push({i, j});
            } else
                bee_dist[i][j] = INF;
    }
        
    while (bee_order.size()) {
        int i = bee_order.front().first, j = bee_order.front().second;
        bee_order.pop();

        vector<pii> delta = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
        for (pii in : delta) {
            int new_i = i + in.first, new_j = j + in.second;
            if (new_i < 1 || new_i > n || new_j < 1 || new_j > n) continue;
            if (arr[new_i][new_j] == 'T' || arr[new_i][new_j] == 'D') continue;
            if (bee_seen[new_i][new_j]) continue;

            bee_seen[new_i][new_j] = true;
            bee_dist[new_i][new_j] = bee_dist[i][j] + 1;
            bee_order.push({new_i, new_j});
        }
    }
}

bool check_seen[MAX_N][MAX_N];
int check_dist[MAX_N][MAX_N]; // INF if unreachable
queue<pii> check_order;
bool check(int t) {
    pii finish = {0, 0};
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++) {
            if (arr[i][j] == 'M') {
                if (bee_dist[i][j] < t) return false;

                check_seen[i][j] = true;
                check_dist[i][j] = 0;
                check_order.push({i, j});
            } else {
                check_seen[i][j] = false;
                check_dist[i][j] = INF;
            }
            if (arr[i][j] == 'D')
                finish = {i, j};
        }
    }
    
    while (check_order.size()) {
        int i = check_order.front().first, j = check_order.front().second;
        check_order.pop();

        // cout << t << ": " << i << " " << j << endl;

        vector<pii> delta = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
        for (pii in : delta) {
            int new_i = i + in.first, new_j = j + in.second;
            if (new_i < 1 || new_i > n || new_j < 1 || new_j > n) continue;
            if (arr[new_i][new_j] == 'T') continue;
            if (check_seen[new_i][new_j]) continue;

            int new_dist = check_dist[i][j] + 1;
            if (bee_dist[new_i][new_j] < t + (new_dist / s)) continue;
            check_dist[new_i][new_j] = new_dist;

            check_seen[new_i][new_j] = true;
            check_order.push({new_i, new_j}); 
        }
    }

    return check_seen[finish.first][finish.second];
}
int bin_search() {
    int lo = 1, hi = MAX_T;
    while (lo != hi) {
        int mid = ceil((lo + hi) / (double) 2);
        if (check(mid)) lo = mid;
        else hi = mid - 1;
    }
    if (check(lo)) return lo;
    else return -1;
}

int main() {
    // freopen("mecho.in", "r", stdin);

    cin >> n >> s;
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= n; j++)
            cin >> arr[i][j];
    
    bee_bfs();

    int ans = bin_search();
    if (ans != -1) ans--;
    cout << ans << '\n';

    // for (int i = 1; i <= n; i++) {
    //     for (int j = 1; j <= n; j++)
    //         cout << bee_dist[i][j] << " ";
    //     cout << endl;
    // }
        
}

Subtask #1
100.0 / 100.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 4444 KB Output is correct
2 Correct 1 ms 4444 KB Output is correct
3 Correct 1 ms 4444 KB Output is correct
4 Correct 1 ms 4444 KB Output is correct
5 Correct 1 ms 4444 KB Output is correct
6 Correct 1 ms 4444 KB Output is correct
7 Correct 149 ms 7320 KB Output is correct
8 Correct 1 ms 4444 KB Output is correct
9 Correct 1 ms 4444 KB Output is correct
10 Correct 1 ms 4444 KB Output is correct
11 Correct 2 ms 4700 KB Output is correct
12 Correct 2 ms 6748 KB Output is correct
13 Correct 1 ms 4700 KB Output is correct
14 Correct 2 ms 6748 KB Output is correct
15 Correct 1 ms 4444 KB Output is correct
16 Correct 2 ms 4444 KB Output is correct
17 Correct 1 ms 4444 KB Output is correct
18 Correct 2 ms 4444 KB Output is correct
19 Correct 1 ms 4444 KB Output is correct
20 Correct 1 ms 4444 KB Output is correct
21 Correct 1 ms 4700 KB Output is correct
22 Correct 1 ms 4700 KB Output is correct
23 Correct 2 ms 4700 KB Output is correct
24 Correct 1 ms 4696 KB Output is correct
25 Correct 2 ms 6748 KB Output is correct
26 Correct 2 ms 6748 KB Output is correct
27 Correct 2 ms 6748 KB Output is correct
28 Correct 2 ms 6748 KB Output is correct
29 Correct 2 ms 6748 KB Output is correct
30 Correct 3 ms 6748 KB Output is correct
31 Correct 2 ms 7000 KB Output is correct
32 Correct 3 ms 6748 KB Output is correct
33 Correct 11 ms 7000 KB Output is correct
34 Correct 15 ms 7004 KB Output is correct
35 Correct 38 ms 7040 KB Output is correct
36 Correct 13 ms 7004 KB Output is correct
37 Correct 17 ms 7004 KB Output is correct
38 Correct 49 ms 7080 KB Output is correct
39 Correct 16 ms 7004 KB Output is correct
40 Correct 21 ms 6960 KB Output is correct
41 Correct 63 ms 7120 KB Output is correct
42 Correct 19 ms 7004 KB Output is correct
43 Correct 24 ms 7316 KB Output is correct
44 Correct 82 ms 7160 KB Output is correct
45 Correct 24 ms 7048 KB Output is correct
46 Correct 29 ms 7004 KB Output is correct
47 Correct 91 ms 7004 KB Output is correct
48 Correct 27 ms 7020 KB Output is correct
49 Correct 34 ms 7236 KB Output is correct
50 Correct 120 ms 6996 KB Output is correct
51 Correct 31 ms 7256 KB Output is correct
52 Correct 41 ms 7512 KB Output is correct
53 Correct 163 ms 7276 KB Output is correct
54 Correct 41 ms 7312 KB Output is correct
55 Correct 47 ms 7152 KB Output is correct
56 Correct 194 ms 7140 KB Output is correct
57 Correct 46 ms 7188 KB Output is correct
58 Correct 53 ms 7572 KB Output is correct
59 Correct 204 ms 7196 KB Output is correct
60 Correct 53 ms 7260 KB Output is correct
61 Correct 59 ms 7392 KB Output is correct
62 Correct 225 ms 7396 KB Output is correct
63 Correct 179 ms 7400 KB Output is correct
64 Correct 300 ms 7392 KB Output is correct
65 Correct 259 ms 7400 KB Output is correct
66 Correct 203 ms 7392 KB Output is correct
67 Correct 186 ms 7252 KB Output is correct
68 Correct 96 ms 7420 KB Output is correct
69 Correct 88 ms 7420 KB Output is correct
70 Correct 87 ms 7424 KB Output is correct
71 Correct 80 ms 7316 KB Output is correct
72 Correct 66 ms 7200 KB Output is correct
73 Correct 75 ms 7672 KB Output is correct
74 Correct 111 ms 7620 KB Output is correct
75 Correct 141 ms 7440 KB Output is correct
76 Correct 119 ms 7496 KB Output is correct
77 Correct 120 ms 7768 KB Output is correct
78 Correct 153 ms 7652 KB Output is correct
79 Correct 107 ms 7508 KB Output is correct
80 Correct 129 ms 7652 KB Output is correct
81 Correct 129 ms 7644 KB Output is correct
82 Correct 140 ms 7648 KB Output is correct
83 Correct 144 ms 7404 KB Output is correct
84 Correct 157 ms 7680 KB Output is correct
85 Correct 137 ms 7504 KB Output is correct
86 Correct 155 ms 7504 KB Output is correct
87 Correct 161 ms 7612 KB Output is correct
88 Correct 161 ms 7552 KB Output is correct
89 Correct 167 ms 7376 KB Output is correct
90 Correct 169 ms 7504 KB Output is correct
91 Correct 166 ms 7556 KB Output is correct
92 Correct 155 ms 7368 KB Output is correct