Submission #169896

#	Time	Username	Problem	Language	Result	Execution time	Memory
169896		stefdasca	Bomb (IZhO17_bomb)	C++14	27 / 100	245 ms	9336 KiB

bomb

#include<bits/stdc++.h>
#define god dimasi5eks
#pragma GCC optimize("O3")
#define fi first
#define se second
#define pb push_back
#define pf push_front
#define mod 1000000007
#define dancila 3.14159265359
#define eps 1e-9

using namespace std;

typedef long long ll;


int add(int a, int b)
{
    ll x = a+b;
    if(x >= mod)
        x -= mod;
    if(x < 0)
        x += mod;
    return x;
}
ll mul(ll a, ll b)
{
    return (a*b) % mod;
}

ll pw(ll a, ll b)
{
    ll ans = 1;
    while(b)
    {
        if(b & 1)
            ans = (ans * a) % mod;
        a = (a * a) % mod;
        b >>= 1;
    }
    return ans;
}
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
long long rand_seed()
{
    long long a = rng();
    return a;
}
char c[2600][2600];
int mars[2600][2600], sp[2600][2600];
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int n, m;
    cin >> n >> m;
    for(int i = 1; i <= n; ++i)
        cin >> (c[i] + 1);
    int xx = 0;
    for(int i = 1; i <= n; ++i)
        for(int j = 1; j <= m; ++j)
            xx += (c[i][j] == '0');
    if(!xx)
    {
        cout << n*m;
        return 0;
    }
    if(n <= 450 && m <= 450)
    {
        for(int i = 1; i <= n; ++i)
        {
            for(int j = 1; j <= m; ++j)
            {
                sp[i][j] = (c[i][j] - '0') + sp[i-1][j] + sp[i][j-1] - sp[i-1][j-1];
            }
        }
        int mxans = 0;
        for(int i = n; i >= 1; --i)
        {
            int mnx = m;
            for(int xx = 1; xx <= n; ++xx)
            {
                int str = 0;
                for(int j = 1; j <= m; ++j)
                {
                    if(c[xx][j] == '1')
                        ++str;
                    else
                    {
                        if(str)
                            mnx = min(mnx, str);
                        str = 0;
                    }
                }
                if(str)
                    mnx = min(mnx, str);
            }
            int j = mnx;
            if(i*j <= mxans)
                continue;
            for(int q = i; q <= n; ++q)
                for(int p = j; p <= m; ++p)
                {
                    if(sp[q][p] - sp[q - i][p] - sp[q][p - j] + sp[q - i][p - j] == i * j)
                    {
                        mars[q - i + 1][p - j + 1]++;
                        mars[q + 1][p - j + 1]--;
                        mars[q - i + 1][p + 1]--;
                        mars[q + 1][p + 1]++;
                    }
                }
            bool ok = 1;
            for(int q = 1; q <= n; ++q)
                for(int p = 1; p <= m; ++p)
                {
                    mars[q][p] = mars[q][p] + mars[q-1][p] + mars[q][p-1] - mars[q-1][p-1];
                    if(c[q][p] == '1' && !mars[q][p])
                    {
                        ok = 0;
                        p = m+1;
                        q = n+1;
                    }
                }
            for(int q = 1; q <= n; ++q)
                for(int p = 1; p <= m; ++p)
                    mars[q][p] = 0;
            if(ok)
                mxans = max(mxans, i*j);
        }
        cout << mxans;
    }
    else
    {
        int mnx = m, mny = n;
        for(int i = 1; i <= n; ++i)
        {
            int str = 0;
            for(int j = 1; j <= m; ++j)
            {
                if(c[i][j] == '1')
                    ++str;
                else
                {
                    if(str)
                        mnx = min(mnx, str);
                    str = 0;
                }
            }
            if(str)
                mnx = min(mnx, str);
        }
        for(int j = 1; j <= m; ++j)
        {
            int str = 0;
            for(int i = 1; i <= n; ++i)
            {
                if(c[i][j] == '1')
                    ++str;
                else
                {
                    if(str)
                        mny = min(mny, str);
                    str = 0;
                }
            }
            if(str)
                mny = min(mny, str);
        }
        cout << mnx * mny << '\n';
    }
    return 0;
}

Compilation message (stderr)

bomb.cpp: In function 'int main()':
bomb.cpp:114:34: warning: assuming signed overflow does not occur when assuming that (X + c) >= X is always true [-Wstrict-overflow]
                 for(int p = 1; p <= m; ++p)
                                ~~^~~~

• Subtask 1: 27 / 100