Submission #686397

#	Time	Username	Problem	Language	Result	Execution time	Memory
686397		pragmatist	Bomb (IZhO17_bomb)	C++17	33 / 100	1102 ms	55604 KiB

bomb

/*
#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("O3")
#pragma GCC target ("avx2")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma GCC optimize("unroll-loops")
*/

#include<bits/stdc++.h>
 
#define ld long double
#define sz(v) (int)v.size()
#define ll long long
#define pb push_back
#define x first
#define y second
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define nl "\n"

using namespace std;

const int N = (int)25e2 + 7; // make sure this is right
const int M = (int)1e6 + 7;
const int B = 351;
const int inf = (int)2e9 + 7;
const ll INF = (ll)3e18 + 7; 
const ll MOD = (ll)1e9 + 7; // make sure this is right

bool bit(int x, int i) {
	return x >> i & 1;
}

int mult(int x, int y) {
	return 1ll * x * y % MOD;
}

int sum(int x, int y) {
	x += y;
	if(x >= MOD) x -= MOD;
	return x;
}

int n, m, p[N][N], e[N][N];
char a[N][N];

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

void solve() {
	cin >> n >> m;
	for(int i = 1; i <= n; ++i) {
		for(int j = 1; j <= m; ++j) {
			cin >> a[i][j];
			p[i][j] = p[i - 1][j] + p[i][j - 1] - p[i - 1][j - 1] + (a[i][j] == '1');
		}
	}
	int ans = 0;                      
	for(int h = 1; h <= n; ++h) {
		int l = 1, r = m;
		while(l <= r) {
    		int w = (l + r) >> 1;
    		for(int i = 1; i <= n -	h + 1; ++i) {
    			for(int j = 1; j <= m - w + 1; ++j) {
					int ii = i + h - 1, jj = j + w - 1;
					int x = get(i, j, ii, jj);
					if(x == h * w) {
						e[i][j]++;
						e[i][jj + 1]--;
						e[ii + 1][j]--;
						e[ii + 1][jj + 1]++;			
    				}	
    			}
    		}
			for(int i = 1; i <= n; ++i) {
				for(int j = 1; j <= m; ++j) {
					e[i][j] += e[i - 1][j];
					e[i][j] += e[i][j - 1];
					e[i][j] -= e[i - 1][j - 1];
				}
			}

			bool ok = 1;
			for(int i = 1; i <= n && ok; ++i) {
				for(int j = 1; j <= m && ok; ++j) {
					if(a[i][j] == '1') {
						ok &= (e[i][j] > 0);
					}
				}
			}
			for(int i = 1; i <= n; ++i) {
				for(int j = 1; j <= m; ++j) {
					e[i][j] = 0;
				}
			}
			if(ok) {
				ans = max(ans, h * w);
				l = w + 1;
			} else
				r = w - 1;
    	}
	}
	cout << ans << "\n";
}
	
signed main() {	
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int test = 1;
	//cin >> test;
	for(int i = 1; i <= test; ++i) {
	 	//cout << "Case #" << i << ": ";
		solve();
	}
	return 0;
}

• Subtask 1: 33 / 100