1751: [Usaco2005 qua]Lake Counting

Time Limit: 5 Sec Memory Limit: 64 MB
Submit: 190 Solved: 150
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Description

Due to recent rains, water has pooled in various places in Farmer John's field, which is represented by a rectangle of N x M (1 <= N <= 100; 1 <= M <= 100) squares. Each square contains either water ('W') or dry land ('.'). Farmer John would like to figure out how many ponds have formed in his field. A pond is a connected set of squares with water in them, where a square is considered adjacent to all eight of its neighbors. Given a diagram of Farmer John's field, determine how many ponds he has.

Input

* Line 1: Two space-separated integers: N and M * Lines 2..N+1: M characters per line representing one row of Farmer John's field. Each character is either 'W' or '.'. The characters do not have spaces between them.

Output

* Line 1: The number of ponds in Farmer John's field.

Sample Input

10 12
W........WW.
.WWW.....WWW
....WW...WW.
.........WW.
.........W..
..W......W..
.W.W.....WW.
W.W.W.....W.
.W.W......W.
..W.......W.

Sample Output

OUTPUT DETAILS:

There are three ponds: one in the upper left, one in the lower left,
and one along the right side.

HINT

Source

Gold

题解：直接萌萌哒DFS秒之，经典的普及组难度基础题，水水哒

(Tip:38行的dfs(a1,a2)貌似只有这样写在本机才能对，提交也能A；很神奇的是如果直接写dfs(i,j)的话在本机就会出现带入的是(1,1)结果进去的是(2,2)QAQ，然后各种神奇跪OTL，更神奇的是这个在本机都跪成狗的程序居然submit之后也能A（QAQ），求神犇解释)

 var

    i,j,k,l,m,n,a1,a2:longint;

    c1:char;

    a:array[..,..] of longint;

 procedure dfs(x,y:longint);inline;

           begin

                a[x,y]:=;

                if a[x-,y-]= then dfs(x-,y-);

                if a[x,y-]= then dfs(x,y-);

                if a[x+,y-]= then dfs(x+,y-);

                if a[x-,y+]= then dfs(x-,y+);

                if a[x,y+]= then dfs(x,y+);

                if a[x+,y+]= then dfs(x+,y+);

                if a[x-,y]= then dfs(x-,y);

                if a[x+,y]= then dfs(x+,y);

           end;

 begin

      readln(n,m);

      fillchar(a,sizeof(a),);

      for i:= to n do

          begin

               for j:= to m do

                   begin

                        read(c1);

                        case c1 of

                             'W':a[i,j]:=;

                             '.':a[i,j]:=;

                        end;

                   end;

               readln;

          end;

      l:=;

      for i:= to n do

          for j:= to m do

              if a[i,j]= then

                 begin

                      a1:=i;a2:=j;

                      inc(l);dfs(a1,a2);

                 end;

      writeln(l);

      readln;

 end.

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1751: [Usaco2005 qua]Lake Counting