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  1. /*
  2.  
  3.  
  4.                  """Bismillahir Rahmanur Rahim"""
  5.  
  6. */
  7. #include<bits/stdc++.h>
  8. using namespace std;
  9. #define pi 2*acos(0.0)
  10. #define ll long long int
  11. #define pb push_back
  12. #define pf push_front
  13. const ll sz = 1000001;
  14. #define mp make_pair
  15. #define ses '\n'
  16. #define stm istringstream
  17. #define gcd __gcd
  18. ll lcm(ll x,ll y){return (x*y)/gcd(x,y);}
  19. #define tin ll T;cin>>T; for(ll o=1;o<=T;o++)
  20. #define tout cout<<"Case "<<o<<": ";
  21. ll dr[]={-1,0,1,0};
  22. ll dc[]={0,1,0,-1};
  23. ll valid(ll r,ll c,ll x,ll y)
  24. {
  25.     if(r>=0 && r<x && c>=0 && c<y)
  26.         return 1;
  27.     else return 0;
  28. }
  29. ll ar[480][480];
  30. ll dis[480][480],vis[480][480];
  31. ll mz,u,v;
  32. void bfs(ll a,ll b,ll x,ll y)
  33. {
  34.      queue<pair<ll,ll> >q;
  35.         q.push({a,b});
  36.         vis[a][b]=1;
  37.         dis[a][b]=0;
  38.         mz=0;
  39.         while(!q.empty())
  40.           {
  41.              ll p,k;
  42.              p=q.front().first;
  43.              k=q.front().second;
  44.              q.pop();
  45.              for(int i=0;i<4;i++)
  46.              {
  47.                  ll r=p+dr[i];
  48.                  ll c=k+dc[i];
  49.  
  50.                  if(valid(r,c,x,y))
  51.                  {
  52.                      if(vis[r][c]==0)
  53.                      {
  54.                          if(ar[r][c]==1)
  55.                             {
  56.                                 vis[r][c]=1;
  57.                                 dis[r][c]=dis[p][k]+1;
  58.                                 if(mz<dis[r][c])
  59.                                     mz=dis[r][c],u=r,v=c;
  60.                                q.push({r,c});
  61.                             }
  62.                      }
  63.                  }
  64.              }
  65.           }
  66. }
  67.  
  68. int main()
  69. {
  70.     //freopen ("input.txt","r",stdin);
  71.    // freopen ("output.txt","w",stdout);
  72.  
  73.     {
  74.         ll x,y,a,b;
  75.         scanf("%lld %lld",&x,&y);
  76.         char c;
  77.  
  78.         for(int i=0;i<y;i++)
  79.             for(int j=0;j<x;j++)
  80.             {
  81.                cin>>c;
  82.                 if(c=='.')
  83.                     ar[i][j]=1,a=i,b=j;
  84.                    else ar[i][j]=2;
  85.             }
  86.           bfs(a,b,y,x);
  87.           mz=0;
  88.           for(int i=0;i<y;i++)
  89.            {
  90.                 for(int j=0;j<x;j++)
  91.                   vis[i][j]=0,dis[i][j]=0;
  92.            }
  93.            bfs(u,v,y,x);
  94.            //cout<<mz<<" "<<u<<" "<<v<<ses;
  95.  
  96.           printf("%lld\n",mz);
  97.  
  98.  
  99.  
  100.  
  101.     }
  102.     return 0;
  103. }
  104. /*   --------------------
  105.     |      ~SOHAN~       |
  106.     |   ~Chandler68~     |
  107.      --------------------
  108.     || VALAR MORGULIS||==|| ALL MEN MUST DIE ||
  109.     \\ Power Is Power//
  110.     || I Can Do This All day ||
  111.     // We are on a Break \\ // How you doin'? \\
  112.     || Say My Name || ~~ || I Am The Who Knocks ||
  113.     // I Am Ted Mosby Architect \\
  114.     || It Is Legen --wait for it -- dary ,Legendary ||
  115.     \\ Penny - Penny - Penny // -- Bazinga
  116.  
  117. */
  118.  
Runtime error #stdin #stdout 0s 5316KB
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Standard input is empty
stdout
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Standard output is empty
https://ideone.com/V3u972
language:
C++14 (gcc 8.3)
created:
4 years ago
visibility:
public

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