Submission #942732

#	Time	Username	Problem	Language	Result	Execution time	Memory
942732		atom	Bomb (IZhO17_bomb)	C++17	7 / 100	492 ms	28668 KiB

bomb

#include "bits/stdc++.h"
// @JASPER'S BOILERPLATE
using namespace std;
using ll = long long;

#ifdef JASPER
#include "debug.h"
#else
#define debug(...) 166
#endif

signed main() {
    cin.tie(0) -> sync_with_stdio(0);

    int n, m;
    cin >> n >> m;
    vector <vector <int>> a(n + 5, vector <int> (m + 5, 0));
    for (int i = 1; i <= n; ++i) {
        for (int j = 1; j <= m; ++j) {
            char x; cin >> x;
            a[i][j] = x - '0';
        }
    }

    // for (int i = 1; i <= n; ++i) 
    //     for (int j = 1; j <= m; ++j)
    //         cout << a[i][j] << " \n"[j == m]; 

    //sub1: shortest consecutive 1ss
    if (n == 1 || m == 1) {
        if (n == 1) {
            int ans = 1e9;
            for (int i = 1; i <= m; ++i) {
                if (a[1][i] == 0) continue;
                int cur = 0;
                while (i <= m && a[1][i]) { 
                    ++cur;
                    ++i;
                }
                ans = min(ans, cur);
            }
            cout << ans << "\n";
            return 0;
        }
        if (m == 1) {
            int ans = 1e9;
            for (int i = 1; i <= n; ++i) {
                if (a[i][1] == 0) continue;
                int cur = 0;
                while (i <= n && a[i][1]) { 
                    ++cur;
                    ++i;
                }
                ans = min(ans, cur);
            }
            cout << ans << "\n";
            return 0;
        }
    }

    // sub4: fixed width
    if (n <= 450 && m <= 450) {
        vector <vector <int>> prf(n + 5, vector <int> (m + 5, 0));
        int earth = 0;
        for (int i = 1; i <= n; ++i) {
            for (int j = 1; j <= m; ++j) {
                earth += (a[i][j] == 0);
                prf[i][j] = prf[i][j - 1] + prf[i - 1][j] - prf[i - 1][j - 1] + a[i][j];
            }
        }

        int y = 1e9;
        for (int i = 1; i <= n; ++i) {
            int d = 0;
            for (int j = 1; j <= m; ++j) {
                (a[i][j]? ++d : d = 0);
                if (d)
                    y = min(y, d); 
            }
        }

        int ans = 0;
        for (int x = 1; x <= n; ++x) {
            if (x * y <= ans) continue;
            // prf(l)++, prf(r + 1)--;
            vector <vector <int>> dmg(n + 2, vector <int> (m + 2, 0));

            for (int i = 1; i + x - 1 <= n; ++i) {
                for (int j = 1; j + y - 1 <= m; ++j) {
                    int I = i + x - 1, J = j + y - 1;
                    if (prf[I][J] + prf[i - 1][j - 1] - prf[I][j - 1] - prf[i - 1][J] == x * y) {
                        dmg[i][j] += 1;
                        dmg[I + 1][j] -= 1;
                        dmg[i][J + 1] -= 1;
                        dmg[I + 1][J + 1] += 1;
                    }
                }
            } 

            for (int i = 1; i <= n; ++i)
                for (int j = 1; j <= m; ++j)
                    dmg[i][j] += dmg[i - 1][j] + dmg[i][j - 1] - dmg[i - 1][j - 1];

            bool valid = 1;
            for (int i = 1; i <= n; ++i) {
                for (int j = 1; j <= m; ++j) {
                    if (a[i][j] && !dmg[i][j])
                        valid = 0;
                }
            }
            if (valid) ans = max(ans, x * y);
        }

        cout << ans << "\n";
    }

}

• Subtask 1: 7 / 100