Submission #172151

#	Time	Username	Problem	Language	Result	Execution time	Memory
172151		MvC	Bomb (IZhO17_bomb)	C++11	50 / 100	1085 ms	103928 KiB

bomb

//#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
#define rc(x) return cout<<x<<endl,0
#define pb push_back
#define mkp make_pair
#define in insert
#define er erase
#define fd find
#define fr first
#define sc second
typedef long long ll;
typedef long double ld;
const ll INF=0x3f3f3f3f3f3f3f3f;
const ll llinf=(1LL<<62);
const int inf=(1<<30);
const int nmax=2505;
const int mod=1e9+7;
using namespace std;
int n,m,i,j,cur,h[nmax][nmax],v[nmax][nmax],x,y,a[nmax][nmax],ad[nmax][nmax],b[nmax][nmax],rs,mid,l,r;
char c;
bool ok(int h,int w)
{
	int i,j,x;
	for(i=1;i<=n;i++)for(j=1;j<=m;j++)ad[i][j]=0;
	for(i=1;i<=n;i++)
	{
		for(j=1;j<=m;j++)
		{
			if(i<=n-h+1 && j<=m-w+1)
			{
				x=b[i+h-1][j+w-1]-b[i+h-1][j-1]-b[i-1][j+w-1]+b[i-1][j-1];
				if(x==h*w)
				{
					ad[i][j]++;
					ad[i][j+w]--;
					ad[i+h][j]--;
					ad[i+h][j+w]++;
				}
			}
			ad[i][j]+=ad[i-1][j]+ad[i][j-1]-ad[i-1][j-1];
			if(!ad[i][j] && a[i][j])return 0;
		}
	}
	return 1;
}
int main()
{
	//freopen("sol.in","r",stdin);
	//freopen("sol.out","w",stdout);
	//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
	ios_base::sync_with_stdio(false);cin.tie(0);cerr.tie(0);cout.tie(0);
	cin>>n>>m;
	for(i=1;i<=n;i++)
	{
		for(j=1;j<=m;j++)
		{
			cin>>c;
			a[i][j]=(c=='1');
			b[i][j]=a[i][j]+b[i-1][j]+b[i][j-1]-b[i-1][j-1];
		}
	}
	x=y=inf;
	for(i=1;i<=n;i++)
	{
		for(j=m;j>=1;j--)
		{
			if(a[i][j])
			{
				h[i][j]=h[i][j+1]+1;
				if(!a[i][j-1])y=min(y,h[i][j]);
			}
		}
	}
	for(i=1;i<=m;i++)
	{
		for(j=n;j>=1;j--)
		{
			if(a[j][i])
			{
				v[j][i]=v[j+1][i]+1;
				if(!a[j-1][i])x=min(x,v[j][i]);
			}
		}
	}
	if(x==inf)rc(0);
	if(n*m>=1e6)rc(x*y);
	for(i=1;i<=x;i++)
	{
		l=1,r=y,cur=0;
		while(l<=r)
		{
			mid=(l+r)/2;
			if(ok(i,mid))cur=mid,l=mid+1;
			else r=mid-1;
		}
		rs=max(rs,i*cur);
	}
	cout<<rs<<endl;
	return 0;
}

• Subtask 1: 50 / 100