1751: [Usaco2005 qua]Lake Counting

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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

3 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)

 1 var
 2    i,j,k,l,m,n,a1,a2:longint;
 3    c1:char;
 4    a:array[0..200,0..200] of longint;
 5 procedure dfs(x,y:longint);inline;
 6           begin
 7                a[x,y]:=0;
 8                if a[x-1,y-1]=1 then dfs(x-1,y-1);
 9                if a[x,y-1]=1 then dfs(x,y-1);
10                if a[x+1,y-1]=1 then dfs(x+1,y-1);
11                if a[x-1,y+1]=1 then dfs(x-1,y+1);
12                if a[x,y+1]=1 then dfs(x,y+1);
13                if a[x+1,y+1]=1 then dfs(x+1,y+1);
14                if a[x-1,y]=1 then dfs(x-1,y);
15                if a[x+1,y]=1 then dfs(x+1,y);
16           end;
17 begin
18      readln(n,m);
19      fillchar(a,sizeof(a),0);
20      for i:=1 to n do
21          begin
22               for j:=1 to m do
23                   begin
24                        read(c1);
25                        case c1 of
26                             'W':a[i,j]:=1;
27                             '.':a[i,j]:=0;
28                        end;
29                   end;
30               readln;
31          end;
32      l:=0;
33      for i:=1 to n do
34          for j:=1 to m do
35              if a[i,j]=1 then
36                 begin
37                      a1:=i;a2:=j;
38                      inc(l);dfs(a1,a2);
39                 end;
40      writeln(l);
41      readln;
42 end.