oj.uz

Submission #395796

# Submission time Handle Problem Language Result Execution time Memory
395796 2021-04-28T23:46:31 Z SirCovidThe19th Mecho (IOI09_mecho) C++14
90 / 100
 213 ms 6264 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;
}
//precompute how far every cell is to the nearest hive
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' or grid[x][y] == 'M') 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;
    //time it takes for bees is floor(bearDist/s)
    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;
    //check if bees can reach mecho before he even moves
    int hiveToStart = hiveDist[start.first][start.second];
    if (wait >= hiveToStart and hiveToStart != -1) return false;
    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];
                //ok, mecho reached home
                if (grid[x][y] == 'D') return true;
                if (inside(x, y) and (grid[x][y] == 'G' or grid[x][y] == 'D') 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;
                    //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();
    //impossible
    if (!bear(0)){
        cout<<-1; return 0;
    }
    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
90.0 / 100.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2764 KB Output is correct
2 Correct 3 ms 2764 KB Output is correct
3 Correct 2 ms 2764 KB Output is correct
4 Correct 2 ms 2764 KB Output is correct
5 Correct 2 ms 2764 KB Output is correct
6 Correct 2 ms 2764 KB Output is correct
7 Incorrect 123 ms 6028 KB Output isn't correct
8 Correct 2 ms 2764 KB Output is correct
9 Correct 2 ms 2764 KB Output is correct
10 Correct 2 ms 2764 KB Output is correct
11 Correct 2 ms 2764 KB Output is correct
12 Correct 2 ms 2764 KB Output is correct
13 Correct 2 ms 2764 KB Output is correct
14 Correct 2 ms 2764 KB Output is correct
15 Correct 2 ms 2764 KB Output is correct
16 Correct 3 ms 2732 KB Output is correct
17 Correct 3 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 2764 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 2764 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 3 ms 2764 KB Output is correct
29 Correct 3 ms 2764 KB Output is correct
30 Correct 3 ms 2764 KB Output is correct
31 Correct 3 ms 2764 KB Output is correct
32 Correct 4 ms 2764 KB Output is correct
33 Correct 15 ms 3448 KB Output is correct
34 Correct 15 ms 3464 KB Output is correct
35 Correct 35 ms 3532 KB Output is correct
36 Correct 16 ms 3668 KB Output is correct
37 Correct 15 ms 3664 KB Output is correct
38 Correct 50 ms 3660 KB Output is correct
39 Correct 22 ms 3928 KB Output is correct
40 Correct 22 ms 3948 KB Output is correct
41 Correct 74 ms 3932 KB Output is correct
42 Correct 22 ms 4172 KB Output is correct
43 Correct 26 ms 4036 KB Output is correct
44 Correct 86 ms 4172 KB Output is correct
45 Correct 26 ms 4300 KB Output is correct
46 Correct 33 ms 4380 KB Output is correct
47 Correct 95 ms 4300 KB Output is correct
48 Correct 33 ms 4596 KB Output is correct
49 Correct 32 ms 4648 KB Output is correct
50 Correct 106 ms 4732 KB Output is correct
51 Correct 36 ms 4932 KB Output is correct
52 Correct 37 ms 4860 KB Output is correct
53 Correct 163 ms 4856 KB Output is correct
54 Correct 50 ms 5168 KB Output is correct
55 Correct 50 ms 5136 KB Output is correct
56 Correct 151 ms 5260 KB Output is correct
57 Correct 47 ms 5480 KB Output is correct
58 Correct 49 ms 5540 KB Output is correct
59 Correct 177 ms 5584 KB Output is correct
60 Correct 54 ms 5848 KB Output is correct
61 Incorrect 53 ms 5820 KB Output isn't correct
62 Correct 213 ms 5872 KB Output is correct
63 Correct 185 ms 5852 KB Output is correct
64 Incorrect 113 ms 5820 KB Output isn't correct
65 Incorrect 116 ms 5916 KB Output isn't correct
66 Correct 195 ms 5956 KB Output is correct
67 Incorrect 133 ms 5844 KB Output isn't correct
68 Correct 98 ms 5868 KB Output is correct
69 Correct 91 ms 6084 KB Output is correct
70 Correct 96 ms 5916 KB Output is correct
71 Correct 89 ms 5948 KB Output is correct
72 Correct 78 ms 6044 KB Output is correct
73 Correct 84 ms 6216 KB Output is correct
74 Correct 123 ms 6228 KB Output is correct
75 Correct 133 ms 6216 KB Output is correct
76 Correct 127 ms 6128 KB Output is correct
77 Correct 124 ms 6100 KB Output is correct
78 Correct 69 ms 6184 KB Output is correct
79 Correct 113 ms 6120 KB Output is correct
80 Correct 127 ms 6084 KB Output is correct
81 Correct 141 ms 6084 KB Output is correct
82 Correct 118 ms 6084 KB Output is correct
83 Correct 155 ms 6264 KB Output is correct
84 Correct 138 ms 6040 KB Output is correct
85 Correct 129 ms 6044 KB Output is correct
86 Correct 136 ms 6140 KB Output is correct
87 Correct 164 ms 6212 KB Output is correct
88 Correct 151 ms 6044 KB Output is correct
89 Correct 151 ms 6084 KB Output is correct
90 Correct 156 ms 6092 KB Output is correct
91 Correct 165 ms 6012 KB Output is correct
92 Correct 142 ms 6056 KB Output is correct