1751: [Usaco2005 qua]Lake Counting
1751: [Usaco2005 qua]Lake Counting
Time Limit: 5 Sec Memory Limit: 64 MB
Submit: 190 Solved: 150
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
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.