Submission #1128734

#	Time	Username	Problem	Language	Result	Execution time	Memory
1128734		_Temirhan	Bomb (IZhO17_bomb)	C++20	20 / 100	1102 ms	124628 KiB

bomb

#include <bits/stdc++.h>

using namespace std;
  
#define int long long
#define pb push_back
#define sz(x) x.size()
#define F first
#define S second
#define nl '\n'

void Tima() 
{
    #ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    #endif
}  

const int N = 3000;
const int inf = 1e12;
const int mod = 1e9 + 7;
int n, m, p[N][N], p1[N][N];
string t[N];

bool ch( int x, int y )
{
    for( int i = 1; i + x - 1 <= n; ++i )
        for( int j = 1; j + y - 1 <= m; ++j )
            if( p[i + x - 1][j + y - 1] - p[i + x - 1][j - 1] - p[i - 1][j + y - 1] + p[i - 1][j - 1] == x * y )
            {
                ++p1[i][j];
                --p1[i + x][j];
                --p1[i][j + y];
                ++p1[i + x][j + y];
            }
    bool ch = true;
    for( int i = 1; i <= n; ++i )
        for( int j = 1; j <= m; ++j )
        {
            p1[i][j] += p1[i - 1][j] + p1[i][j - 1] - p1[i - 1][j - 1];
            if( !p1[i][j] && t[i - 1][j - 1] == '1' )
                ch = false;
        }
    for( int i = 1; i <= n + 1; ++i )
        for( int j = 1; j <= m + 1; ++j )
            p1[i][j] = 0;
    return ch;
}

signed main() 
{
    // Tima();
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cin >>n >>m;
    for( int i = 0; i < n; ++i )
    {
        cin >>t[i];
        for( int j = 0; j < m; ++j )
            if( t[i][j] == '1' )
                ++p[i + 1][j + 1];
    }
    for( int i = 1; i <= n; ++i )
        for( int j = 1; j <= m; ++j )
            p[i][j] += p[i - 1][j] + p[i][j - 1] - p[i - 1][j - 1];
    int l = 1, r = n, mid;
    while( l + 1 < r )
    {
        mid = (l + r) / 2;
        if( ch(mid, 1) )
            l = mid;
        else
            r = mid;
    }
    int len = l;
    if( ch(r, 1) )
        len = r;
    l = 1;
    r = m;
    while( l + 1 < r )
    {
        mid = (l + r) / 2;
        if( ch(len, mid) )
            l = mid;
        else
            r = mid;
    }
    if( ch(len, r) )
        l = r;
    int ans = len * l;
    l = 1;
    r = m;
    while( l + 1 < r )
    {
        mid = (l + r) / 2;
        if( ch(1, mid) )
            l = mid;
        else
            r = mid;
    }
    if( ch(1, r) )
        l = r;
    len = l;
    l = 1;
    r = n;
    while( l + 1 < r )
    {
        mid = (l + r) / 2;
        if( ch(mid, len) )
            l = mid;
        else
            r = mid;
    }
    if( ch(r, len) )
        l = r;
    ans = max(ans, l * len);
    cout <<ans;
}

Compilation message (stderr)

bomb.cpp: In function 'void Tima()':
bomb.cpp:15:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   15 |     freopen("input.txt", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
bomb.cpp:16:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |     freopen("output.txt", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 20 / 100