Submission #474288

#	Time	Username	Problem	Language	Result	Execution time	Memory
474288		ogibogi2004	Bomb (IZhO17_bomb)	C++14	90 / 100	472 ms	56900 KiB

bomb

#include<bits/stdc++.h>
using namespace std;
const int MAXN=2502;
char t[MAXN][MAXN];
int n,m,maxw,maxh;
vector<pair<int,int> >segments[MAXN];
vector<pair<int,int> >mws[MAXN];
int up[MAXN][MAXN];
int down[MAXN][MAXN];
int ans[MAXN];
int main()
{
    cin>>n>>m;
    maxh=n;
    maxw=m;
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=m;j++)
        {
            cin>>t[i][j];
        }
    }
    for(int i=1;i<=n;i++)
    {
        ans[i]=n*m;
        int cnt=0;
        for(int j=1;j<=m;j++)
        {
            ans[j]=n*m;
            if(t[i][j]=='1')cnt++;
            else
            {
                if(cnt>0)maxw=min(maxw,cnt);
                cnt=0;
            }
        }
        if(cnt>0)maxw=min(maxw,cnt);
    }
    //cout<<maxw<<endl;
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=m;j++)
        {
            if(t[i][j]=='0')up[i][j]=-1;
            else
            {
                if(up[i-1][j]>0)up[i][j]=up[i-1][j];
                else up[i][j]=i;
            }
        }
    }
    for(int i=n;i>=1;i--)
    {
        for(int j=1;j<=m;j++)
        {
            if(t[i][j]=='0')down[i][j]=-1;
            else
            {
                if(down[i+1][j]>0)down[i][j]=down[i+1][j];
                else down[i][j]=i;
            }
        }
    }
    for(int i=1;i<=n;i++)
    {
        int cnt=0;
        for(int j=1;j<=m;j++)
        {
            if(t[i][j]=='0')
            {
                if(cnt>0)mws[i].push_back({j-cnt,j-1});
                cnt=0;
            }
            else cnt++;
        }
        if(cnt>0)mws[i].push_back({m-cnt+1,m});
    }
    /*for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=m;j++)
        {
            cout<<up[i][j]<<" ";
        }
        cout<<endl;
    }
    cout<<endl;
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=m;j++)
        {
            cout<<down[i][j]<<" ";
        }
        cout<<endl;
    }
    cout<<endl;*/
    for(int i=1;i<=n;i++)
    {
        //cout<<i<<":\n";
        for(int j=0;j<mws[i].size();j++)
        {
            int start=mws[i][j].first;
            int mindown=n+1,maxup=-1;
            for(int len=1;start+len-1<=mws[i][j].second;len++)
            {
                mindown=min(mindown,down[i][start+len-1]);
                maxup=max(maxup,up[i][start+len-1]);
                //cout<<mws[i][j].first<<" "<<len<<" "<<mindown<<" "<<maxup<<endl;
                //cout<<mindown<<" "<<maxup<<endl;
                //cout<<mindown<<" "<<maxup<<endl;
                ans[len]=min(ans[len],len*(mindown-maxup+1));
            }
            start=mws[i][j].second;
            mindown=n+1;maxup=-1;
            for(int len=1;start-len+1>=mws[i][j].first;len++)
            {
                mindown=min(mindown,down[i][start-len+1]);
                maxup=max(maxup,up[i][start-len+1]);
                //cout<<mws[i][j].second<<" "<<len<<" "<<mindown<<" "<<maxup<<endl;
                ans[len]=min(ans[len],len*(mindown-maxup+1));
            }
        }
    }
    if(maxw==0)
    {
        cout<<0<<endl;
        return 0;
    }
    int ans1=0;
    for(int i=1;i<=maxw;i++)
    {
        //cout<<ans[i]<<" ";
        ans1=max(ans1,ans[i]);
    }
    //cout<<endl;
    cout<<ans1<<endl;
return 0;
}

Compilation message (stderr)

bomb.cpp: In function 'int main()':
bomb.cpp:99:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   99 |         for(int j=0;j<mws[i].size();j++)
      |                     ~^~~~~~~~~~~~~~

• Subtask 1: 90 / 100