Depth First search: satellite photographs

Description

Farmer John purchased satellite photos of W x H pixels of his farm (1 <= W <=, 1 <= H <=) and wishes T o Determine the largest ' contiguous ' (connected) pasture. Pastures is contiguous when any pair of the pixels in a pasture can is connected by traversing adjacent vertical or Horizonta L pixels that is part of the pasture. (It's easy-to-create pastures with very strange shapes, even circles that surround and other circles.)

Each photo have been digitally enhanced to show pasture area as an asterisk (' * ') and non-pasture area as a period ('. '). Here is a ten X 5 sample satellite Photo:

.. *.....**
.**.. *****
.*...*....
.. ****.***
.. ****.***

This photo shows three contiguous pastures of 4, 6 pixels. Help FJ find the largest contiguous pasture in all of his satellite photos.

Input

* Line 1:two space-separated integers:w and H

* Lines 2..h+1:each line contains W "*" or "." Characters representing one raster line of a satellite photograph.

Output

* Line 1:the size of the largest contiguous field in the satellite photo.

Sample Input

10 5..*.....**.**. *****.*...*......****.***.. ****.***

Sample Output

16

1#include <cstdio>2#include <iostream>3#include <cstring>4#include <string>5#include <algorithm>6 7 using namespacestd;8 9 Const intX[] = {0,0, -1,1 };Ten Const intY[] = {-1,1,0,0 }; One  A Const intMAX =1010; - CharArr[max][max]; - BOOLVis[max][max]; the  - intW, H; - inttmp, ans; -  + voidDFS (intXinty); -  + intMain () A { at #ifdef OFFLINE -Freopen ("In.txt","R", stdin); -Freopen ("OUT.txt","W", stdout); - #endif -  -      while(~SCANF ("%d%d", &w, &h)) in     { -memset (arr,0,sizeof(arr)); tomemset (Vis,false,sizeof(Vis)); +          for(inti =0; I < H; i++) -scanf"%s", Arr[i]); the  *Ans =0; $          for(inti =0; I < H; i++)Panax Notoginseng         { -              for(intj =0; J < W; J + +) the             { +                 if(Arr[i][j] = ='*'&&!Vis[i][j]) A                 { theTMP =0; + DFS (i, j); -Ans =max (ans, tmp); $                 } $             } -         } -  theprintf"%d\n", ans); -     }Wuyi  the     return 0; - } Wu  - voidDFS (intXinty) About { $Vis[x][y] =true; -  -      for(inti =0; I <4; i++) -     { A         intNX = x + x[i], NY = y +Y[i]; +         if(NX >=0&& NX < h && NY >=0&& NY < w && Arr[nx][ny] = ='*'&&!Vis[nx][ny]) the         { - DFS (NX, NY); $         } the     } the  thetmp++; the     return; -}

View Code

Depth First search: satellite photographs