Submission #173102

#	Time	Username	Problem	Language	Result	Execution time	Memory
173102		VEGAnn	Bomb (IZhO17_bomb)	C++14	41 / 100	1108 ms	102280 KiB

bomb

#include <bits/stdc++.h>
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("-O3")
#pragma GCC optimize("Ofast")
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define sz(x) ((int)x.size())
#define MP make_pair
#define ft first
#define sd second
#define pii pair<int, int>
#define PB push_back
using namespace std;
using namespace __gnu_pbds;
template <class T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const int N = 2510;
const int oo = 2e9;
int n, m, ans, a[N][N], pref[N][N], vl[N][N], pl[N][N];

bool ok(int ht, int wd){
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++)
            pl[i][j] = 0;

    for (int i = 1; i <= n; i++)
    for (int j = 1; j <= m; j++){
        if (i + ht - 1 > n || j + wd - 1 > m)
            break;
        int i1 = i + ht - 1, i2 = i - 1;
        int j1 = j + wd - 1, j2 = j - 1;
        int kol = pref[i1][j1] - pref[i2][j1] - pref[i1][j2] + pref[i2][j2];

        if (kol > 0) continue;

        pl[i][j]++; pl[i][j + wd]--;
        pl[i + ht][j]--; pl[i + ht][j + wd]++;

    }

    for (int i = 1; i <= n; i++){
        int cr = 0;
        for (int j = 1; j <= m; j++){
            cr += pl[i][j];
            vl[i][j] = cr;
        }
    }

    for (int j = 1; j <= m; j++){
        int cr = 0;
        for (int i = 1; i <= n; i++){
            cr += vl[i][j];
            if (a[i][j] == 1 && cr == 0)
                return 0;
        }
    }

    return 1;
}

int main(){
    ios_base::sync_with_stdio(0); cin.tie(0);
//    freopen("in.txt","r",stdin);
    cin >> n >> m;
    for (int i = 1; i <= n; i++)
    for (int j = 1; j <= m; j++){
        char c; cin >> c;
        a[i][j] = (c == '1' ? 1 : 0);
        pref[i][j] = (a[i][j] ^ 1) + pref[i - 1][j] + pref[i][j - 1] - pref[i - 1][j - 1];
    }

    int wd = m;
    for (int ht = 1; ht <= n; ht++){
        while (wd > 0 && !ok(ht, wd))
            wd--;
        if (wd == 0) break;
        ans = max(ans, ht * wd);
    }

    cout << ans;

    return 0;
}

• Subtask 1: 41 / 100