1751: [Usaco2005 qua]Lake Counting

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)

var
i,j,k,l,m,n,a1,a2:longint;
c1:char;
a:array[0..200,0..200] of longint;
procedure dfs(x,y:longint);inline;
begin
a[x,y]:=0;
if a[x-1,y-1]=1 then dfs(x-1,y-1);
if a[x,y-1]=1 then dfs(x,y-1);
if a[x+1,y-1]=1 then dfs(x+1,y-1);
if a[x-1,y+1]=1 then dfs(x-1,y+1);
if a[x,y+1]=1 then dfs(x,y+1);
if a[x+1,y+1]=1 then dfs(x+1,y+1);
if a[x-1,y]=1 then dfs(x-1,y);
if a[x+1,y]=1 then dfs(x+1,y);
end;
begin
readln(n,m);
fillchar(a,sizeof(a),0);
for i:=1 to n do
begin
for j:=1 to m do
begin
read(c1);
case c1 of
'W':a[i,j]:=1;
'.':a[i,j]:=0;
end;
end;
readln;
end;
l:=0;
for i:=1 to n do
for j:=1 to m do
if a[i,j]=1 then
begin
a1:=i;a2:=j;
inc(l);dfs(a1,a2);
end;
writeln(l);
readln;
end.