Submission #173232

#	Time	Username	Problem	Language	Result	Execution time	Memory
173232		VEGAnn	Bomb (IZhO17_bomb)	C++14	100 / 100	573 ms	75540 KiB

bomb

#include <bits/stdc++.h>
#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], mx = oo, pr[N][N], best[N], nt[N][N], mnw = oo;

int main(){
    ios_base::sync_with_stdio(0); cin.tie(0);
    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);
    }

    for (int j = 1; j <= m; j++){
        for (int i = 1; i <= n; ){
            if (a[i][j] == 0)
                i++;
            else {
                int i1 = i;
                while (i1 <= n && a[i1][j] == 1)
                    i1++;
                mx = min(mx, i1 - i);
                i = i1;
            }
        }
    }

    for (int i = 1; i <= n; i++){
        for (int j = 1; j <= m; ){
            if (a[i][j] == 0)
                j++;
            else {
                int i1 = j;
                while (i1 <= m && a[i][i1] == 1)
                    i1++;
                mnw = min(mnw, i1 - j);
                j = i1;
            }
        }
    }

    fill(best, best + n + 1, oo);

    for (int i = 1; i <= n; i++){
        int pre = 0;
        for (int j = 1; j <= m; j++){
            if (a[i][j] == 0)
                pre = j;
            pr[i][j] = pre + 1;
        }

        pre = m + 1;
        for (int j = m; j > 0; j--){
            if (a[i][j] == 0)
                pre = j;
            nt[i][j] = pre - 1;
        }
    }

    for (int j = 1; j <= m; j++){
        int lf = 0, rt = m + 1, len = 0;
        for (int i = 1; i <= n; i++)
            if (a[i][j] == 1){
                lf = max(lf, pr[i][j]);
                rt = min(rt, nt[i][j]);
                len++;
                best[len] = min(best[len], rt - lf + 1);
            } else {
                len = lf = 0;
                rt = m + 1;
            }

        lf = 0, rt = m + 1, len = 0;
        for (int i = n; i > 0; i--)
            if (a[i][j] == 1){
                lf = max(lf, pr[i][j]);
                rt = min(rt, nt[i][j]);
                len++;
                best[len] = min(best[len], rt - lf + 1);
            } else {
                len = lf = 0;
                rt = m + 1;
            }
    }

    for (int i = 1; i <= mx; i++) {
        if (best[i] == oo) return -1;
        ans = max(ans, min(mnw, best[i]) * i);
    }

    cout << ans << '\n';

    return 0;
}

• Subtask 1: 100 / 100