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Submission #917217

# Submission time Handle Problem Language Result Execution time Memory
917217 2024-01-27T13:01:20 Z vanea Mecho (IOI09_mecho) C++14
100 / 100
 157 ms 7768 KB 
#include <bits/stdc++.h>
using namespace std;
using ll = long long;

const int mxN = 801;
int n, s;
vector<string> field(mxN);
bool vis1[mxN][mxN], vis2[mxN][mxN];
int d1[mxN][mxN], d2[mxN][mxN];

vector<int> xy = {1, 0, -1, 0}, yx = {0, 1, 0, -1};

bool valid(int x, int y) {
    return (x >= 0 && x < n && y >= 0 && y < n && (field[x][y] == 'G'
                                                || field[x][y] == 'M'));
}

void bfs1(queue<array<int, 2>> &q) {
    while(!q.empty()) {
        auto x = q.front()[0], y = q.front()[1];
        q.pop();
        for(int k = 0; k < 4; k++) {
            int a = x + xy[k], b = y + yx[k];
            if(valid(a, b) && !vis1[a][b]) {
                vis1[a][b] = true; d1[a][b] = d1[x][y]+1;
                q.push({a, b});
            }
        }
    }
}

bool reaches(int a, int b) {
    return a/s < b;
}

void bfs2(queue<array<int, 2>> &q, int t) {
    while(!q.empty()) {
        auto x = q.front()[0], y = q.front()[1];
        q.pop();
        for(int k = 0; k < 4; k++) {
            int a = x + xy[k], b = y + yx[k];
            if(valid(a, b) && !vis2[a][b] && reaches(d2[x][y]+1, d1[a][b] - t)) {
                vis2[a][b] = true;
                d2[a][b] = d2[x][y] + 1;
                q.push({a, b});
            }
        }
    }
}

void restart() {
    memset(vis2, false, sizeof vis2);
    memset(d2, 0, sizeof d2);
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cin >> n >> s;
    vector<array<int, 2>> hives;
    array<int, 2> start, finish;
    for(int i = 0; i < n; i++) {
        cin >> field[i];
        for(int j = 0; j < n; j++) {
            if(field[i][j] == 'M') {
                start = {i, j};
            }
            else if(field[i][j] == 'H') {
                hives.push_back({i, j});
            }
            else if(field[i][j] == 'D') {
                finish = {i, j};
            }
        }
    }
    queue<array<int, 2>> q;
    for(auto it : hives) {
        q.push(it);
        vis1[it[0]][it[1]] = true;
    }
    bfs1(q);
    int l = 0, r = n*n;
    while(l <= r) {
        int mid = (l+r)/2;
        restart();
        q.push(start);
        if(d1[start[0]][start[1]] <= mid) q.pop();
        vis2[start[0]][start[1]] = true;
        bfs2(q, mid);
        bool can = false;
        for(int k = 0; k < 4; k++) {
            int a = finish[0] + xy[k], b = finish[1] + yx[k];
            if(valid(a, b) && vis2[a][b] &&
               reaches(d2[a][b], d1[a][b]-mid)) {
                can = true;
            }
        }
        if(can) l = mid+1;
        else r = mid-1;
    }
    cout << l-1;
}

Compilation message

mecho.cpp: In function 'int main()':
mecho.cpp:93:60: warning: 'finish.std::array<int, 2>::_M_elems[1]' may be used uninitialized in this function [-Wmaybe-uninitialized]
   93 |             int a = finish[0] + xy[k], b = finish[1] + yx[k];
      |                                                            ^
mecho.cpp:93:37: warning: 'finish.std::array<int, 2>::_M_elems[0]' may be used uninitialized in this function [-Wmaybe-uninitialized]
   93 |             int a = finish[0] + xy[k], b = finish[1] + yx[k];
      |                                     ^

Subtask #1
100.0 / 100.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 3416 KB Output is correct
2 Correct 1 ms 3420 KB Output is correct
3 Correct 1 ms 3420 KB Output is correct
4 Correct 2 ms 3420 KB Output is correct
5 Correct 1 ms 3420 KB Output is correct
6 Correct 2 ms 3420 KB Output is correct
7 Correct 54 ms 7476 KB Output is correct
8 Correct 2 ms 3672 KB Output is correct
9 Correct 2 ms 3676 KB Output is correct
10 Correct 1 ms 3676 KB Output is correct
11 Correct 2 ms 3676 KB Output is correct
12 Correct 2 ms 3676 KB Output is correct
13 Correct 2 ms 3676 KB Output is correct
14 Correct 2 ms 3676 KB Output is correct
15 Correct 2 ms 3676 KB Output is correct
16 Correct 2 ms 3676 KB Output is correct
17 Correct 2 ms 3676 KB Output is correct
18 Correct 2 ms 3676 KB Output is correct
19 Correct 2 ms 3676 KB Output is correct
20 Correct 2 ms 3676 KB Output is correct
21 Correct 2 ms 3676 KB Output is correct
22 Correct 2 ms 3676 KB Output is correct
23 Correct 2 ms 3676 KB Output is correct
24 Correct 2 ms 3676 KB Output is correct
25 Correct 2 ms 3676 KB Output is correct
26 Correct 2 ms 3676 KB Output is correct
27 Correct 2 ms 3676 KB Output is correct
28 Correct 2 ms 3676 KB Output is correct
29 Correct 2 ms 3928 KB Output is correct
30 Correct 2 ms 3676 KB Output is correct
31 Correct 2 ms 3932 KB Output is correct
32 Correct 2 ms 3932 KB Output is correct
33 Correct 5 ms 4956 KB Output is correct
34 Correct 5 ms 4952 KB Output is correct
35 Correct 16 ms 4952 KB Output is correct
36 Correct 6 ms 5212 KB Output is correct
37 Correct 6 ms 5212 KB Output is correct
38 Correct 22 ms 5368 KB Output is correct
39 Correct 8 ms 5464 KB Output is correct
40 Correct 7 ms 5468 KB Output is correct
41 Correct 27 ms 5624 KB Output is correct
42 Correct 7 ms 5724 KB Output is correct
43 Correct 8 ms 5724 KB Output is correct
44 Correct 37 ms 5724 KB Output is correct
45 Correct 8 ms 5980 KB Output is correct
46 Correct 9 ms 5980 KB Output is correct
47 Correct 44 ms 6100 KB Output is correct
48 Correct 9 ms 6236 KB Output is correct
49 Correct 11 ms 6236 KB Output is correct
50 Correct 53 ms 6484 KB Output is correct
51 Correct 10 ms 6492 KB Output is correct
52 Correct 11 ms 6492 KB Output is correct
53 Correct 58 ms 6492 KB Output is correct
54 Correct 12 ms 6744 KB Output is correct
55 Correct 12 ms 6744 KB Output is correct
56 Correct 65 ms 6876 KB Output is correct
57 Correct 13 ms 7004 KB Output is correct
58 Correct 15 ms 7000 KB Output is correct
59 Correct 71 ms 7000 KB Output is correct
60 Correct 14 ms 7260 KB Output is correct
61 Correct 15 ms 7260 KB Output is correct
62 Correct 91 ms 7420 KB Output is correct
63 Correct 82 ms 7416 KB Output is correct
64 Correct 157 ms 7412 KB Output is correct
65 Correct 110 ms 7256 KB Output is correct
66 Correct 87 ms 7424 KB Output is correct
67 Correct 83 ms 7256 KB Output is correct
68 Correct 34 ms 7260 KB Output is correct
69 Correct 43 ms 7252 KB Output is correct
70 Correct 32 ms 7260 KB Output is correct
71 Correct 37 ms 7256 KB Output is correct
72 Correct 27 ms 7252 KB Output is correct
73 Correct 21 ms 7512 KB Output is correct
74 Correct 57 ms 7768 KB Output is correct
75 Correct 48 ms 7716 KB Output is correct
76 Correct 40 ms 7516 KB Output is correct
77 Correct 48 ms 7516 KB Output is correct
78 Correct 50 ms 7512 KB Output is correct
79 Correct 37 ms 7512 KB Output is correct
80 Correct 44 ms 7516 KB Output is correct
81 Correct 50 ms 7576 KB Output is correct
82 Correct 43 ms 7636 KB Output is correct
83 Correct 61 ms 7640 KB Output is correct
84 Correct 55 ms 7512 KB Output is correct
85 Correct 63 ms 7640 KB Output is correct
86 Correct 61 ms 7512 KB Output is correct
87 Correct 67 ms 7640 KB Output is correct
88 Correct 67 ms 7580 KB Output is correct
89 Correct 60 ms 7384 KB Output is correct
90 Correct 73 ms 7580 KB Output is correct
91 Correct 63 ms 7576 KB Output is correct
92 Correct 68 ms 7580 KB Output is correct