Submission #180297

#	Time	Username	Problem	Language	Result	Execution time	Memory
180297		srvlt	Bomb (IZhO17_bomb)	C++14	100 / 100	748 ms	123740 KiB

bomb

//#pragma GCC optimize("Ofast")
//#pragma GCC target("avx,avx2,fma")
#include <bits/stdc++.h>

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ordered_set tree <pair <int, int>, null_type, less <pair <int, int> >, rb_tree_tag, tree_order_statistics_node_update>
using namespace __gnu_pbds;

#define ll long long
#define db double
#define pb push_back
#define ppb pop_back
#define fi first
#define se second
#define mp make_pair
#define size(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()

#define endl "\n"
//#define int long long

using namespace std;

void dout() {
    cerr << endl;
}
template <typename Head, typename... Tail>
void dout(Head H, Tail... T) {
    cerr << H << ' ';
    dout(T...);
}

//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
typedef pair <int, int> pii;

const int N = 2503, inf = 1e4;
int n, m, a[N][N], top[N][N], bot[N][N];
int h[N], W = inf, H = inf, row[N][N], col[N][N];

void solve(int tc) {
    // check for (int i = 0; i < n; j++)
    cin >> n >> m;
    char c;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= m; j++) {
            cin >> c;
            if (c == '1') {
                a[i][j] = 1;
            }
        }
    }
    for (int i = 1; i <= m; i++) {
        bot[n + 1][i] = n + 1;
    }
    for (int j = 1; j <= m; j++) {
        for (int i = 1; i <= n; i++) {
            top[i][j] = top[i - 1][j];
            if (!a[i][j]) {
                top[i][j] = i;
            }
        }
        for (int i = n; i >= 1; i--) {
            bot[i][j] = bot[i + 1][j];
            if (!a[i][j]) {
                bot[i][j] = i;
            }
        }
    }

    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= m; j++) {
            if (a[i][j]) {
                row[i][j] = row[i][j - 1] + 1;
            }   else {
                if (row[i][j - 1] > 0) {
                    W = min(W, row[i][j - 1]);
                }
            }
        }
        if (row[i][m] > 0) {
            W = min(W, row[i][m]);
        }
    }
    for (int j = 1; j <= m; j++) {
        for (int i = 1; i <= n; i++) {
            if (a[i][j]) {
                col[i][j] = col[i - 1][j] + 1;
            }   else {
                if (col[i - 1][j] > 0) {
                    H = min(H, col[i - 1][j]);
                }
            }
        }
        if (col[n][j] > 0) {
            H = min(H, col[n][j]);
        }
    }

    for (int i = 1; i <= m; i++) {
        h[i] = H;
    }

    for (int i = 1; i <= n; i++) {
        int last = -1, mn = inf, mx = -inf;
        for (int j = 1; j <= m; j++) {
            if (!a[i][j]) {
                last = -1;
                mn = inf, mx = -inf;
            }   else {
                if (last == -1) {
                    last = j;
                }
                mn = min(mn, bot[i][j]);
                mx = max(mx, top[i][j]);
                h[j - last + 1] = min(h[j - last + 1], mn - mx - 1);
            }
        }
        last = -1, mn = inf, mx = -inf;
        for (int j = m; j >= 1; j--) {
            if (!a[i][j]) {
                last = -1;
                mn = inf, mx = -inf;
            }   else {
                if (last == -1) {
                    last = j;
                }
                mn = min(mn, bot[i][j]);
                mx = max(mx, top[i][j]);
                h[last - j + 1] = min(h[last - j + 1], mn - mx - 1);
            }
        }
    }
    int mn = inf, mx = 0;
    for (int i = 1; i <= W; i++) {
        mn = h[i];
        mx = max(mx, mn * i);
    }
    cout << mx;
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
//    freopen("input.txt", "r", stdin);
//    freopen("output.txt", "w", stdout);
    int tc = 1;
//    cin >> tc;
    for (int i = 0; i < tc; i++) {
        solve(i);
//        cleanup();
    }
}

• Subtask 1: 100 / 100