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Submission #395792

# Submission time Handle Problem Language Result Execution time Memory
395792 2021-04-28T23:20:20 Z SirCovidThe19th Mecho (IOI09_mecho) C++14
68 / 100
 248 ms 6852 KB 
#include <bits/stdc++.h>
using namespace std;

int n, s;
int dx[4] = {1, -1, 0, 0}; int dy[4] = {0, 0, -1, 1};
int hiveDist[800][800];
char grid[800][800];

pair<int, int> start;
pair<int, int> dest;
vector<pair<int, int>> hives;

bool inside(int x, int y){
    return x >= 0 and x < n and y >= 0 and y < n;
}
bool checkDone(int x, int y){
    //check if bear is next to his home
    return (abs(x-dest.first) == 1 and y-dest.second == 0) or
           ((x-dest.first) == 0 and abs(y-dest.second) == 1);
}
void bees(){
    queue<pair<int, int>> trav;
    fill(&hiveDist[0][0], &hiveDist[0][0]+sizeof(hiveDist)/sizeof(hiveDist[0][0]), -1);
    for (pair<int, int> loc : hives){
        trav.push(loc); 
        hiveDist[loc.first][loc.second] = 0;
    }
    while (!trav.empty()){
        pair<int, int> curr = trav.front(); trav.pop();
        for (int i = 0; i < 4; i++){
            int x = curr.first+dx[i]; int y = curr.second+dy[i];
            if (inside(x, y) and grid[x][y] == 'G' and hiveDist[x][y] == -1){
                hiveDist[x][y] = hiveDist[curr.first][curr.second]+1;
                trav.push({x, y});
            }
        }
    }
}
bool bear(int wait){
    queue<pair<int, int>> trav;
    //floor(bearDist/s) = time
    int bearDist[n][n];
    fill(&bearDist[0][0], &bearDist[0][0]+sizeof(bearDist)/sizeof(bearDist[0][0]), -1);
    trav.push(start); bearDist[start.first][start.second] = wait*s;

    while (!trav.empty()){
        pair<int, int> curr = trav.front(); trav.pop();
        //smoll bfs on reachable positions
        queue<pair<int, int>> pos; pos.push(curr);
        while (!pos.empty()){
            pair<int, int> loc = pos.front(); pos.pop();
            for (int i = 0; i < 4; i++){
                int x = loc.first+dx[i]; int y = loc.second+dy[i];
                if (inside(x, y) and grid[x][y] == 'G' and bearDist[x][y] == -1){
                    bearDist[x][y] = bearDist[loc.first][loc.second]+1;
                    //uh oh, bees can reach here before you can
                    if (floor(bearDist[x][y]/s) >= hiveDist[x][y] and hiveDist[x][y] != -1) continue;
                    if (checkDone(x, y)) return true;
                    //max distance reached
                    int maxDist = (bearDist[curr.first][curr.second]/s)+1;
                    if (bearDist[x][y] == maxDist)
                        trav.push({x, y});
                    else
                        pos.push({x, y});
                }
            }
        }
    }
    return false;
}
int main() {

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

    bees();
    
    int high = n*n; int low = 0; int ans;
    while (low < high){
        int mid = (low+high)/2;
        if (bear(mid)){
            ans = mid; low = mid+1;
        }
        else 
            high = mid;
    }
    cout<<ans;
}

Compilation message

mecho.cpp: In function 'int main()':
mecho.cpp:94:11: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
   94 |     cout<<ans;
      |           ^~~

Subtask #1
68.0 / 100.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2764 KB Output is correct
2 Correct 2 ms 2764 KB Output is correct
3 Correct 2 ms 2764 KB Output is correct
4 Correct 2 ms 2712 KB Output is correct
5 Correct 3 ms 2764 KB Output is correct
6 Correct 2 ms 2764 KB Output is correct
7 Correct 158 ms 6588 KB Output is correct
8 Incorrect 2 ms 2764 KB Output isn't correct
9 Correct 2 ms 2764 KB Output is correct
10 Correct 3 ms 2764 KB Output is correct
11 Correct 2 ms 2764 KB Output is correct
12 Incorrect 3 ms 2764 KB Output isn't correct
13 Incorrect 3 ms 2764 KB Output isn't correct
14 Incorrect 3 ms 2764 KB Output isn't correct
15 Correct 2 ms 2764 KB Output is correct
16 Correct 2 ms 2764 KB Output is correct
17 Correct 2 ms 2764 KB Output is correct
18 Correct 2 ms 2764 KB Output is correct
19 Correct 2 ms 2764 KB Output is correct
20 Correct 2 ms 2768 KB Output is correct
21 Correct 2 ms 2764 KB Output is correct
22 Correct 2 ms 2764 KB Output is correct
23 Correct 2 ms 2864 KB Output is correct
24 Correct 2 ms 2764 KB Output is correct
25 Correct 2 ms 2764 KB Output is correct
26 Correct 2 ms 2764 KB Output is correct
27 Correct 2 ms 2764 KB Output is correct
28 Correct 2 ms 2764 KB Output is correct
29 Correct 2 ms 2872 KB Output is correct
30 Correct 2 ms 2764 KB Output is correct
31 Correct 2 ms 2892 KB Output is correct
32 Correct 3 ms 2868 KB Output is correct
33 Correct 13 ms 3648 KB Output is correct
34 Correct 12 ms 3660 KB Output is correct
35 Correct 35 ms 3648 KB Output is correct
36 Correct 15 ms 3788 KB Output is correct
37 Correct 18 ms 3768 KB Output is correct
38 Correct 50 ms 3788 KB Output is correct
39 Correct 18 ms 4072 KB Output is correct
40 Correct 18 ms 4092 KB Output is correct
41 Correct 62 ms 4140 KB Output is correct
42 Correct 25 ms 4364 KB Output is correct
43 Correct 23 ms 4380 KB Output is correct
44 Correct 74 ms 4416 KB Output is correct
45 Correct 26 ms 4676 KB Output is correct
46 Correct 27 ms 4632 KB Output is correct
47 Correct 95 ms 4672 KB Output is correct
48 Correct 32 ms 4960 KB Output is correct
49 Correct 32 ms 4932 KB Output is correct
50 Correct 100 ms 5020 KB Output is correct
51 Correct 36 ms 5280 KB Output is correct
52 Correct 37 ms 5316 KB Output is correct
53 Correct 133 ms 5360 KB Output is correct
54 Correct 42 ms 5700 KB Output is correct
55 Correct 49 ms 5616 KB Output is correct
56 Correct 151 ms 5660 KB Output is correct
57 Correct 48 ms 6084 KB Output is correct
58 Correct 48 ms 6052 KB Output is correct
59 Correct 179 ms 6128 KB Output is correct
60 Correct 54 ms 6468 KB Output is correct
61 Correct 53 ms 6420 KB Output is correct
62 Correct 213 ms 6552 KB Output is correct
63 Correct 164 ms 6548 KB Output is correct
64 Correct 248 ms 6584 KB Output is correct
65 Correct 238 ms 6548 KB Output is correct
66 Correct 182 ms 6524 KB Output is correct
67 Incorrect 182 ms 6496 KB Output isn't correct
68 Correct 95 ms 6536 KB Output is correct
69 Correct 83 ms 6656 KB Output is correct
70 Correct 89 ms 6468 KB Output is correct
71 Correct 82 ms 6532 KB Output is correct
72 Incorrect 74 ms 6484 KB Output isn't correct
73 Incorrect 126 ms 6724 KB Output isn't correct
74 Correct 108 ms 6724 KB Output is correct
75 Correct 119 ms 6788 KB Output is correct
76 Correct 114 ms 6848 KB Output is correct
77 Correct 121 ms 6776 KB Output is correct
78 Incorrect 146 ms 6852 KB Output isn't correct
79 Correct 97 ms 6724 KB Output is correct
80 Correct 114 ms 6804 KB Output is correct
81 Correct 133 ms 6852 KB Output is correct
82 Correct 132 ms 6740 KB Output is correct
83 Correct 152 ms 6760 KB Output is correct
84 Correct 128 ms 6736 KB Output is correct
85 Correct 126 ms 6724 KB Output is correct
86 Correct 137 ms 6716 KB Output is correct
87 Correct 137 ms 6688 KB Output is correct
88 Correct 147 ms 6720 KB Output is correct
89 Correct 142 ms 6716 KB Output is correct
90 Correct 159 ms 6648 KB Output is correct
91 Correct 151 ms 6596 KB Output is correct
92 Correct 143 ms 6620 KB Output is correct