Submission #1305360

#	Time	Username	Problem	Language	Result	Execution time	Memory
1305360		Davdav1232	Nautilus (BOI19_nautilus)	C++20	66 / 100	1095 ms	1084 KiB

nautilus

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

static unsigned char cur[500][500];
static unsigned char nxt[500][500];
static unsigned char blocked[500][500];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int r, c, m;
    cin >> r >> c >> m;

    // read grid
    for (int i = 0; i < r; i++) {
        string s;
        cin >> s;
        for (int j = 0; j < c; j++) {
            blocked[i][j] = (s[j] == '#');
            cur[i][j] = !blocked[i][j]; // start anywhere not blocked
        }
    }

    string way;
    cin >> way;

    for (int step = 0; step < m; step++) {
        char w = way[step];
        memset(nxt, 0, sizeof(nxt));

        if (w == '?') {
            // propagate all 4 directions
            for (int i = 0; i < r; i++)
                for (int j = 0; j < c; j++)
                    if (cur[i][j]) {
                        if (i)       nxt[i-1][j] = 1;
                        if (i+1 < r) nxt[i+1][j] = 1;
                        if (j)       nxt[i][j-1] = 1;
                        if (j+1 < c) nxt[i][j+1] = 1;
                    }
        }
        else if (w == 'N') {
            for (int i = 0; i+1 < r; i++)
                for (int j = 0; j < c; j++)
                    nxt[i][j] = cur[i+1][j];
        }
        else if (w == 'S') {
            for (int i = 1; i < r; i++)
                for (int j = 0; j < c; j++)
                    nxt[i][j] = cur[i-1][j];
        }
        else if (w == 'E') {
            for (int i = 0; i < r; i++)
                for (int j = 1; j < c; j++)
                    nxt[i][j] = cur[i][j-1];
        }
        else if (w == 'W') {
            for (int i = 0; i < r; i++)
                for (int j = 0; j+1 < c; j++)
                    nxt[i][j] = cur[i][j+1];
        }

        // apply obstacles + detect emptiness
        bool any = false;
        for (int i = 0; i < r; i++) {
            for (int j = 0; j < c; j++) {
                nxt[i][j] &= !blocked[i][j];
                any |= nxt[i][j];
            }
        }

        if (!any) {
            cout << 0;
            return 0;
        }

        // swap buffers
        memcpy(cur, nxt, sizeof(cur));
    }

    int ans = 0;
    for (int i = 0; i < r; i++)
        for (int j = 0; j < c; j++)
            ans += cur[i][j];

    cout << ans;
    return 0;
}

• Subtask 1: 29 / 29
• Subtask 2: 37 / 37
• Subtask 3: 0 / 34