Submission #803129

#	Time	Username	Problem	Language	Result	Execution time	Memory
803129		Liudas	Mecho (IOI09_mecho)	C++17	100 / 100	239 ms	5216 KiB

mecho

#include <bits/stdc++.h>

using namespace std;

int main()
{
    int N, S;
    cin >> N >> S;
    vector<string> _map(N + 2);
    string t = string(N+2, 'T');
    _map[0] = t;
    _map[N+1] = t;
    for(int i = 1; i <= N; i ++){
        cin >> _map[i];
        _map[i] = "T"+_map[i] + "T";
    }
    int sx, sy, ex, ey;
    vector<pair<int, int>> bees;
    for(int i = 1; i <= N;  i++){
        for(int j = 1; j <= N; j ++){
            if(_map[i][j] == 'M'){
                sx = j;
                sy = i;
                _map[i][j]='G';
            }
            if(_map[i][j] == 'D'){
                ex = j;
                ey = i;
            }
            if(_map[i][j] == 'H'){
                _map[i][j] == 'T';
                bees.push_back({i, j});
            }
        }
    }
    vector<int> dx = {1,-1,0,0}, dy = {0,0,1,-1};
    int l = -1, r = N * N + 10;
    bool gr = false;
    while(l + 1 < r){
        int mid = (l + r) / 2;
        //cout << mid << " " << l << " " << r << endl;
        vector<string> arr = _map;
        vector<vector<int>> been(N + 2, vector<int>(N + 2));
        queue<pair<int, int>> bee, bee2, moves;
        moves.push({sy, sx});
        for(auto[l, r] : bees){
            bee.push({l, r});
        }
        bool reach = false;
        for(int j = 0; j < mid; j ++){
            while(!bee.empty()){
                int a = bee.front().first, b = bee.front().second;
                bee.pop();
                for(int i = 0; i < 4; i ++){
                    if(arr[a+dy[i]][b+dx[i]] == 'G'){
                        arr[a+dy[i]][b+dx[i]] = 'T';
                        bee2.push({a+dy[i], b+dx[i]});
                    }
                }
            }
            swap(bee, bee2);
        }
        int it = 0;
        while(!moves.empty() && !reach){
            while(!moves.empty()){
                int a = moves.front().first, b = moves.front().second;
                //cout << a << " " << b << " " << mid << endl;
                if(been[a][b] >= (it + 1) * S)break;
                if(arr[a][b]=='D'){reach = true;gr = true;break;}
                moves.pop();
                //cout << arr[a][b] << endl;
                if(arr[a][b] == 'T')continue;
                for(int i = 0; i < 4; i ++){
                   // cout << a + dy[i] << " " << endl;
                    if(!been[a+dy[i]][b+dx[i]] && arr[a+dy[i]][b+dx[i]] != 'T'){
                        been[a+dy[i]][b+dx[i]] = been[a][b] + 1;
                        moves.push({a+dy[i], b+dx[i]});
                    }
                }
            }
            //cout << " ?" << endl;
            while(!bee.empty()){
                int a = bee.front().first, b = bee.front().second;
                bee.pop();
                for(int i = 0; i < 4; i ++){
                    if(arr[a+dy[i]][b+dx[i]] == 'G'){
                        arr[a+dy[i]][b+dx[i]] = 'T';
                        bee2.push({a+dy[i], b+dx[i]});
                    }
                }
            }
            swap(bee, bee2);
            it++;
        }
        if(reach){
            l = mid;
        }
        else{
            r = mid;
        }
    }
    cout << l << endl;
    return 0;
}

Compilation message (stderr)

mecho.cpp: In function 'int main()':
mecho.cpp:31:28: warning: value computed is not used [-Wunused-value]
   31 |                 _map[i][j] == 'T';
mecho.cpp:17:17: warning: variable 'ex' set but not used [-Wunused-but-set-variable]
   17 |     int sx, sy, ex, ey;
      |                 ^~
mecho.cpp:17:21: warning: variable 'ey' set but not used [-Wunused-but-set-variable]
   17 |     int sx, sy, ex, ey;
      |                     ^~
mecho.cpp:38:10: warning: variable 'gr' set but not used [-Wunused-but-set-variable]
   38 |     bool gr = false;
      |          ^~

• Subtask 1: 100 / 100