Submission #496231

#	Time	Username	Problem	Language	Result	Execution time	Memory
496231		CaoHuuKhuongDuy	Nafta (COI15_nafta)	C++14	100 / 100	351 ms	66392 KiB

nafta

#include <iostream>
#include <stdio.h>
#include <cstring>
#include <queue>
using namespace std;
#define int long long
#define endl '\n'
const int N=2e3+9;
typedef pair <int,int> ii;
char a[N][N];
bool check[N][N];
int n,m,cost[N][N],f[N][N],dem;
int dx[4]={0,0,-1,1};
int dy[4]={1,-1,0,0};
bool inside(int x,int y)
{
    return (x>=1&&x<=n&&y>=1&&y<=m);
}
void bfs(int x,int y,int &maxx)
{
    maxx=0;
    int xnew,ynew;
    queue <ii> q;
    q.push({x,y});
    check[x][y]=true;
    while (!q.empty())
      {
        x=q.front().first;
        y=q.front().second;
        dem+=a[x][y]-'0';
        maxx=max(maxx,y);
       // cout<<x<<" "<<y<<" "<<a[x][y]<<endl;
        q.pop();
        for (int i=0;i<=3;i++)
          {
            xnew=x+dx[i];
            ynew=y+dy[i];
            if (check[xnew][ynew]||!inside(xnew,ynew)) continue;
            check[xnew][ynew]=true;
            q.push({xnew,ynew});
          }
      }
}
void dp(int k,int lfind,int rfind,int l,int r)
{
    if (l>r) return;
    int mid=(l+r)/2;
    int lim=min(mid-1,rfind),pos;
    for (int i=lfind;i<=lim;i++)
      {
        int tmp=f[k-1][i]+cost[i+1][mid];;
        if (f[k][mid]<tmp)
          {
            f[k][mid]=tmp;
            pos=i;
          }
      }
    //  cout<<pos<<endl;
     // cout<<f[1][1]<<" "<<k<<" "<<mid<<endl;
    dp(k,lfind,pos,l,mid-1);
    dp(k,pos,rfind,mid+1,r);
}
signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    //freopen("test.inp","r",stdin);
    cin>>n>>m;
    for (int i=1;i<=n;i++)
      for (int j=1;j<=m;j++)
        {
          cin>>a[i][j];
          if (a[i][j]=='.') check[i][j]=true;
        }
    for (int j=1;j<=m;j++)
      {
        for (int i=1;i<=n;i++)
          if (!check[i][j]) 
            {
              dem=0;
              int maxx;
              bfs(i,j,maxx);
              cost[j][j]+=dem;
              cost[j][maxx+1]-=dem;
            }
      }
    for (int i=1;i<=m;i++)
      for (int j=i;j<=m;j++)
        cost[i][j]+=cost[i][j-1];
    memset(f,-1,sizeof(f));
    for (int i=0;i<=m;i++)
      f[0][i]=0;
    for (int i=m;i>=1;i--)
      for (int j=i;j<=m;j++)
        cost[i][j]+=cost[i+1][j];
    for (int i=1;i<=m;i++)
    {
      dp(i,0,m,1,m);
      //break;
    }
    //cout<<cost[4][5]<<endl;
    for (int i=1;i<=m;i++)
    {
      int maxx=0;
      for (int j=1;j<=m;j++)
        maxx=max(maxx,f[i][j]);
      cout<<maxx<<endl;
    }
    return 0;
}

Compilation message (stderr)

nafta.cpp: In function 'void dp(long long int, long long int, long long int, long long int, long long int)':
nafta.cpp:60:7: warning: 'pos' may be used uninitialized in this function [-Wmaybe-uninitialized]
   60 |     dp(k,lfind,pos,l,mid-1);
      |     ~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 23 / 23
• Subtask 3: 66 / 66