1751: [Usaco2005 qua]Lake Counting
Time Limit: 5 Sec Memory Limit: 64 MBSubmit: 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 begin18 readln(n,m);19 fillchar(a,sizeof(a),0);20 for i:=1 to n do21 begin22 for j:=1 to m do23 begin24 read(c1);25 case c1 of26 '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 do34 for j:=1 to m do35 if a[i,j]=1 then36 begin37 a1:=i;a2:=j;38 inc(l);dfs(a1,a2);39 end;40 writeln(l);41 readln;42 end.