Submission #854585

#	Time	Username	Problem	Language	Result	Execution time	Memory
854585		The_Samurai	Bomb (IZhO17_bomb)	C++17	38 / 100	1102 ms	55892 KiB

bomb

#include "bits/stdc++.h"
using namespace std;
using ll = long long;
const int inf = 1e9, N = 1e6 + 5;

struct Fenwick_2d {
    vector<vector<int>> tree;
    int l1, l2;

    void init(int n, int m) {
        l1 = n; l2 = m;
        tree.assign(l1 + 1, vector<int>(l2 + 1, 0));
    }

    void update(int x, int y, int v) {
        x++; y++;
        for (; x <= l1; x += x & (-x)) {
            for (int yy = y; yy <= l2; yy += yy & (-yy)) {
                tree[x][yy] += v;
            }
        }
    }

    int get(int x, int y) {
        x++; y++;
        int sum = 0;
        for (; x > 0; x -= x & (-x)) {
            for (int yy = y; yy > 0; yy -= yy & (-yy)) {
                sum += tree[x][yy];
            }
        }
        return sum;
    }

    int get(int x1, int y1, int x2, int y2) {
        return get(x2, y2) - get(x2, y1 - 1) - get(x1 - 1, y2) + get(x1 - 1, y1 - 1);
    }
};

int main() {
    cin.tie(0)->sync_with_stdio(false);
#ifdef sunnatov
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#else
//    freopen("game.in", "r", stdin);
//    freopen("game.out", "w", stdout);
#endif

    int n, m;
    cin >> n >> m;
    vector<vector<char>> a(n + 1, vector<char>(m + 1));
    Fenwick_2d fw; fw.init(n + 1, m + 1);
    for (int i = 1; i <= n; i++) for (int j = 1; j <= m; j++) {
        cin >> a[i][j];
        if (a[i][j] == '1') fw.update(i, j, 1);
    }
    vector<vector<int>> checked(n + 1, vector<int>(m + 1));
    int z = 0;
    auto check = [&](int h, int w) {
        z++;
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= m; j++) {
                if (a[i][j] == '0') continue;
                if (i + h - 1 <= n and j + w - 1 <= m and fw.get(i, j, i + h - 1, j + w - 1) == h * w) {
                    for (int x = i; x < i + h; x++) {
                        for (int y = j; y < j + w; y++) {
                            checked[x][y] = z;
                        }
                    }
                }
                if (checked[i][j] < z) return false;
            }
        }
        return true;
    };
    vector<int> best(n + 1, -1);
    auto get = [&](int h) {
        if (best[h] != -1) return best[h];
        int lx = 1, rx = (h > 1 ? best[h - 1] : m);
        best[h] = 0;
        while (lx <= rx) {
            int mid = (lx + rx) >> 1;
            if (check(h, mid)) {
                best[h] = mid;
                lx = mid + 1;
            } else {
                rx = mid - 1;
            }
        }
        return best[h];
    };
    int ans = 0;
    for (int i = 1; i <= n; i++) ans = max(ans, get(i) * i);
    cout << ans;
}

• Subtask 1: 38 / 100