Submission #173276

#	Time	Username	Problem	Language	Result	Execution time	Memory
173276		apostoldaniel854	Bomb (IZhO17_bomb)	C++14	100 / 100	508 ms	55672 KiB

bomb

#include <bits/stdc++.h>

using namespace std;

const int N = 2500;

char a[1 + N][1 + N];
int lst[1 + N + 1][1 + N + 1];
int nxt[1 + N + 1][1 + N + 1];
int best[1 + N];

int main () {
   // freopen ("bomb.in", "r", stdin);
  //  freopen ("bomb.out", "w", stdout);

    ios::sync_with_stdio (false);
    cin.tie (0); cout.tie (0);

    int n, m;
    cin >> n >> m;

    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++)
            cin >> a[i][j], a[i][j] -= '0';

    int mxl = n;
    for (int j = 1; j <= m; j++)
        for (int i = 1; i <= n; i++) {
            if (a[i][j] == 0)
                continue;
            int k = i;
            while (k <= n && a[k + 1][j] == 1)
                k++;
            mxl = min (mxl, k - i + 1);
            i = k;
        }
    int mxc = m;
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++) {
            if (a[i][j] == 0)
                continue;
            int k = j;
            while (k <= m && a[i][k + 1] == 1)
                k++;
            mxc = min (mxc, k - j + 1);
            j = k;
        }

    for (int i = 1; i <= n; i++) {
        lst[i][0] = 1;
        for (int j = 1; j <= m; j++) {
            lst[i][j] = lst[i][j - 1];
            if (a[i][j] == 0)
                lst[i][j] = j + 1;
        }
        nxt[i][m + 1] = m;
        for (int j = m; j > 0; j--) {
            nxt[i][j] = nxt[i][j + 1];
            if (a[i][j] == 0)
                nxt[i][j] = j - 1;
        }
    }

    for (int i = 1; i <= n; i++)
        best[i] = m + 1;

    for (int j = 1; j <= m; j++) {
        int cur = 0;
        int l = 0, r = m + 1;
        for (int i = 1; i <= n; i++) {
            if (a[i][j] == 0) {
                cur = 0;
                l = 0, r = m + 1;
            }
            else {
                cur++;
                l = max (l, lst[i][j]);
                r = min (r, nxt[i][j]);
                best[cur] = min (best[cur], r - l + 1);
            }
        }
        cur = 0;
        l = 0, r = m + 1;
        for (int i = n; i > 0; i--) {
            if (a[i][j] == 0) {
                cur = 0;
                l = 0, r = m + 1;
            }
            else {
                cur++;
                l = max (l, lst[i][j]);
                r = min (r, nxt[i][j]);
                best[cur] = min (best[cur], r - l + 1);
            }
        }
    }

    int ans = 0;
    for (int i = 1; i <= mxl; i++)
        ans = max (ans, min (mxc, best[i]) * i);
    cout << ans << "\n";
    return 0;
}

• Subtask 1: 100 / 100