oj.uz

Submission #100616

# Submission time Handle Problem Language Result Execution time Memory
100616 2019-03-12T21:00:02 Z ahmedie404 Mecho (IOI09_mecho) C++14
100 / 100
 291 ms 21880 KB 
#include<bits/stdc++.h>
using namespace std;

#define MAX_N 2000

int cx[4] = {1, -1, 0, 0};
int cy[4] = {0, 0, 1, -1};

char mainMap[MAX_N][MAX_N];
bool reachable[MAX_N][MAX_N];

// The time that it takes the bees to reach any cell in the map
int beeDistance[MAX_N][MAX_N];

int n, s;
int dx, dy;
int mx, my;

/**
 * Tests if Mecho is able to reach his home after staying with
 * the honey for the given delay time.
 */
bool test(int delay){
    // Check if the bees catch Mecho whilst he is still with
    // the honey.
    if (delay * s >= beeDistance[mx][my])
        return false;

    // Initialise data structures -- at the beginning of the search,
    // Mecho has only reached the cell with the honey. Note that it
    // is possible for the bees to catch Mecho at the honey -- but
    // we checked for this case above, and so if we reach this point
    // we know that Mecho is safe with the honey after the given
    // delay.
    memset(reachable, 0, sizeof(reachable));
    deque<pair<int, pair<int, int> > > q;
    q.push_back(make_pair(delay * s, make_pair(mx, my)));
    reachable[mx][my] = true;

    // Now do the main loop to see what other cells Mecho can reach.
    while (!q.empty())
    {
        int distance = q.front().first;
        int x = q.front().second.first;
        int y = q.front().second.second;

        q.pop_front();

        // If Mecho has reached his home, then we are done.
        if (mainMap[x][y] == 'D')
            return true;

        // Check neighbouring cells
        for (int c = 0; c < 4; c++)
        {
            int nx = x + cx[c];
            int ny = y + cy[c];

            // Check that the cell is valid, that it is not a tree, and
            // that Mecho can get here before the bees.
            if (nx < 0 || nx >= n || ny < 0 || ny >= n || mainMap[nx][ny] == 'T' || (distance + 1) >= beeDistance[nx][ny] || reachable[nx][ny])
                continue;

            // All OK, so add it to the queue
            q.push_back(make_pair(distance + 1, make_pair(nx, ny)));
            reachable[nx][ny] = true;
        }
    }

    // If we reach here, then Mecho was unable to reach his home.
    return false;
}
int main(int argc, char **argv)
{
    // Read in the data
    cin >> n >> s;

    deque<pair<int, int> > bq;
    memset(beeDistance, -1, sizeof(beeDistance));

    for (int i = 0; i < n; i++)
    {
        cin >> ws;
        for (int j = 0; j < n; j++)
        {
            cin >> mainMap[i][j];
            if (mainMap[i][j] == 'H')
            {
                bq.push_back(make_pair(i, j));
                beeDistance[i][j] = 0;
            }
            else if (mainMap[i][j] == 'M')
            {
                mx = i;
                my = j;

                // Bees can travel through the location of the honey
                mainMap[i][j] = 'G';
            }
            else if (mainMap[i][j] == 'D')
            {
                dx = i;
                dy = j;
            }
        }
    }

    // Precompute the time that it takes the bees to reach any other
    // cell in the map.
    while (!bq.empty())
    {
        int x = bq.front().first;
        int y = bq.front().second;

        bq.pop_front();

        for (int c = 0; c < 4; c++)
        {
            int nx = x + cx[c];
            int ny = y + cy[c];

            if (nx < 0 || nx >= n || ny < 0 || ny >= n || mainMap[nx][ny] != 'G' || beeDistance[nx][ny] != -1)
                continue;

            beeDistance[nx][ny] = beeDistance[x][y] + s;
            bq.push_back(make_pair(nx, ny));
        }
    }

    // The bees can never enter Mecho's home, so set this to a large
    // sentinel value.
    beeDistance[dx][dy] = n * n * s;

    // Binary search to find the maximum delay time.
    int low = -1, high = 2 * n * n;
    while (high - low > 1)
    {
        int mid = (low + high) >> 1;
        if (test(mid))
            low = mid;
        else
            high = mid;
    }

    cout << low << endl;
    return 0;
}

Subtask #1
100.0 / 100.0

# Verdict Execution time Memory Grader output
1 Correct 23 ms 19840 KB Output is correct
2 Correct 18 ms 19960 KB Output is correct
3 Correct 18 ms 19840 KB Output is correct
4 Correct 21 ms 19968 KB Output is correct
5 Correct 18 ms 19940 KB Output is correct
6 Correct 19 ms 19840 KB Output is correct
7 Correct 179 ms 21768 KB Output is correct
8 Correct 17 ms 19840 KB Output is correct
9 Correct 17 ms 19968 KB Output is correct
10 Correct 17 ms 19924 KB Output is correct
11 Correct 20 ms 19968 KB Output is correct
12 Correct 18 ms 20048 KB Output is correct
13 Correct 17 ms 19968 KB Output is correct
14 Correct 18 ms 20048 KB Output is correct
15 Correct 19 ms 19968 KB Output is correct
16 Correct 17 ms 19968 KB Output is correct
17 Correct 18 ms 19968 KB Output is correct
18 Correct 20 ms 19968 KB Output is correct
19 Correct 21 ms 19968 KB Output is correct
20 Correct 19 ms 19968 KB Output is correct
21 Correct 18 ms 19968 KB Output is correct
22 Correct 19 ms 19968 KB Output is correct
23 Correct 21 ms 19968 KB Output is correct
24 Correct 18 ms 19996 KB Output is correct
25 Correct 21 ms 20000 KB Output is correct
26 Correct 21 ms 19968 KB Output is correct
27 Correct 20 ms 19968 KB Output is correct
28 Correct 21 ms 20096 KB Output is correct
29 Correct 21 ms 19968 KB Output is correct
30 Correct 20 ms 19968 KB Output is correct
31 Correct 20 ms 20076 KB Output is correct
32 Correct 22 ms 19968 KB Output is correct
33 Correct 29 ms 20728 KB Output is correct
34 Correct 29 ms 20728 KB Output is correct
35 Correct 43 ms 20624 KB Output is correct
36 Correct 41 ms 20836 KB Output is correct
37 Correct 40 ms 20732 KB Output is correct
38 Correct 56 ms 20728 KB Output is correct
39 Correct 47 ms 20856 KB Output is correct
40 Correct 34 ms 20828 KB Output is correct
41 Correct 79 ms 20956 KB Output is correct
42 Correct 44 ms 21112 KB Output is correct
43 Correct 38 ms 20988 KB Output is correct
44 Correct 101 ms 20984 KB Output is correct
45 Correct 43 ms 21112 KB Output is correct
46 Correct 45 ms 21340 KB Output is correct
47 Correct 101 ms 21112 KB Output is correct
48 Correct 43 ms 21112 KB Output is correct
49 Correct 44 ms 21152 KB Output is correct
50 Correct 112 ms 21268 KB Output is correct
51 Correct 46 ms 21240 KB Output is correct
52 Correct 47 ms 21240 KB Output is correct
53 Correct 132 ms 21376 KB Output is correct
54 Correct 50 ms 21368 KB Output is correct
55 Correct 82 ms 21368 KB Output is correct
56 Correct 219 ms 21496 KB Output is correct
57 Correct 89 ms 21496 KB Output is correct
58 Correct 62 ms 21496 KB Output is correct
59 Correct 176 ms 21548 KB Output is correct
60 Correct 64 ms 21624 KB Output is correct
61 Correct 64 ms 21624 KB Output is correct
62 Correct 194 ms 21624 KB Output is correct
63 Correct 166 ms 21624 KB Output is correct
64 Correct 291 ms 21624 KB Output is correct
65 Correct 203 ms 21752 KB Output is correct
66 Correct 175 ms 21624 KB Output is correct
67 Correct 171 ms 21624 KB Output is correct
68 Correct 129 ms 21672 KB Output is correct
69 Correct 93 ms 21612 KB Output is correct
70 Correct 95 ms 21616 KB Output is correct
71 Correct 85 ms 21624 KB Output is correct
72 Correct 72 ms 21624 KB Output is correct
73 Correct 78 ms 21880 KB Output is correct
74 Correct 108 ms 21880 KB Output is correct
75 Correct 124 ms 21848 KB Output is correct
76 Correct 112 ms 21880 KB Output is correct
77 Correct 106 ms 21880 KB Output is correct
78 Correct 137 ms 21752 KB Output is correct
79 Correct 103 ms 21836 KB Output is correct
80 Correct 123 ms 21752 KB Output is correct
81 Correct 132 ms 21752 KB Output is correct
82 Correct 110 ms 21800 KB Output is correct
83 Correct 138 ms 21876 KB Output is correct
84 Correct 133 ms 21752 KB Output is correct
85 Correct 152 ms 21836 KB Output is correct
86 Correct 140 ms 21752 KB Output is correct
87 Correct 139 ms 21880 KB Output is correct
88 Correct 198 ms 21752 KB Output is correct
89 Correct 144 ms 21752 KB Output is correct
90 Correct 154 ms 21780 KB Output is correct
91 Correct 146 ms 21752 KB Output is correct
92 Correct 158 ms 21788 KB Output is correct