Submission #1248864

#	Time	Username	Problem	Language	Result	Execution time	Memory
1248864		Ghulam_Junaid	Mecho (IOI09_mecho)	C++20	25 / 100	291 ms	11740 KiB

mecho

#include <bits/stdc++.h>
using namespace std;

const int N = 1005;
int n, s, dist[N][N];
char mat[N][N];
pair<int, int> bst[N][N];

bool valid(int x, int y){
    return (x >= 0 and x < n and y >= 0 and y < n and mat[x][y] != 'T');
}

int dx[4] = {0, 1, 0, -1};
int dy[4] = {1, 0, -1, 0};

void bfs(){
    memset(dist, 31, sizeof dist);
    queue<pair<int, int>> q;
    for (int i = 0; i < n; i ++){
        for (int j = 0; j < n; j ++){
            if (mat[i][j] == 'H'){
                dist[i][j] = 0;
                q.push({i, j});
            }
        }
    }

    while (!q.empty()){
        auto [x, y] = q.front();
        q.pop();

        for (int i = 0; i < 4; i ++){
            int nx = x + dx[i];
            int ny = y + dy[i];

            if (!valid(nx, ny) or dist[nx][ny] <= dist[x][y] + 1)
                continue;
            if (mat[nx][ny] == 'D') continue;

            dist[nx][ny] = dist[x][y] + 1;
            q.push({nx, ny});
        }
    }
}

void dijkstra(){
    int sx, sy;
    for (int x = 0; x < n; x ++){
        for (int y = 0; y < n; y ++){
            bst[x][y] = {1e9, 0};
            if (mat[x][y] == 'M')
                sx = x, sy = y;
        }
    }

    set<pair<pair<int, int>, pair<int, int>>> st;
    st.insert({{0 - dist[sx][sy], 0}, {sx, sy}});
    bst[sx][sy] = {0 - dist[sx][sy], 0};

    int ans = dist[sx][sy];
    while (!st.empty()){
        auto [P, Q] = *st.begin();
        auto [val, steps] = P;
        auto [x, y] = Q;
        st.erase(st.begin());
        ans = min(ans, -val);

        for (int i = 0; i < 4; i ++){
            int nx = x + dx[i];
            int ny = y + dy[i];

            if (!valid(nx, ny) or mat[nx][ny] == 'H') continue;
            int nd = ((steps + s) / s) - dist[nx][ny];
            if (bst[nx][ny].first > nd){
                st.erase({bst[nx][ny], {nx, ny}});
                bst[nx][ny] = {nd, steps + 1};
                st.insert({bst[nx][ny], {nx, ny}});
            }

            if (mat[nx][ny] == 'D'){
                if (ans <= 0) ans = -1;
                cout << ans << endl;
                return ;
            }
        }
    }
}

int main(){
    cin >> n >> s;
    for (int i = 0; i < n; i ++)
        for (int j = 0; j < n; j ++)
            cin >> mat[i][j];
    bfs();
    dijkstra();
}

• Subtask 1: 25 / 100