题目：
如下图12×12方格图，找出一条自入口（2，9）到出口（11，8）的最短路径。
Sample Input
12 //迷宫大小
2 9 11 8 //起点和终点
1 1 1 1 1 1 1 1 1 1 1 1 //邻接矩阵，0表示通，1表示不通
1 0 0 0 0 0 0 1 0 1 1 1
1 0 1 0 1 1 0 0 0 0 0 1
1 0 1 0 1 1 0 1 1 1 0 1
1 0 1 0 0 0 0 0 1 0 0 1
1 0 1 0 1 1 1 1 1 1 1 1
1 0 0 0 1 0 1 0 0 0 0 1
1 0 1 1 1 0 0 0 1 1 1 1
1 0 0 0 0 0 1 0 0 0 0 1
1 1 1 0 1 1 1 1 0 1 0 1
1 1 1 1 1 1 1 0 0 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1
Sample Output
(2,9)->(3,9)->(3,8)->(3,7)->(4,7)->(5,7)->(5,6)->(5,5)->(5,4)->(6,4)->(7,4)->(7,3)->(7,2)->(8,2)->(9,2)->(9,3)->(9,4)->(9,5)->(9,6)->(8,6)->(8,7)->(8,8)->(9,8)->(9,9)->(10,9)->(11,9)->(11,8)
27
题解：
这道题可用深搜和广搜，但广搜效率高。
我们上下左右搜。
代码如下：
const
maxn=12;
wayn=4;
dx:array[1..wayn] of integer=(-1,0,1,0);
dy:array[1..wayn] of integer=(0,1,0,-1);
var px,py,qx,qy,s,last:integer;
a:array[0..maxn+1,0..maxn+1] of integer;
father:array[1..maxn*maxn] of integer;
state:array[1..maxn*maxn,1..2] of integer;
procedure init;
var i,j,n:integer;
begin
readln(n);
read(px,py);
readln(qx,qy);
for i:=1 to n do
begin
for j:=1 to n do
read(a[i,j]);
readln;
end;
end;
function check(x,y:integer):boolean;
begin
check:=true;
if (x<1) or (x>12) or (y<1) or (y>12) then check:=false;
if a[x,y]=1 then check:=false;
end;
procedure print(x:integer);
begin
if x=0 then exit;
inc(s);
print(father[x]);
if x<>last then write('(',state[x,1],',',state[x,2],')->')
else writeln('(',state[x,1],',',state[x,2],')')
end;
procedure bfs;
var tail,head,k,i:integer;
begin
head:=0;tail:=1;state[1,1]:=px;state[1,2]:=py;
father[1]:=0;
repeat
head:=head+1;
for k:=1 to wayn do
if check(state[head,1]+dx[k],state[head,2]+dy[k]) then
begin
tail:=tail+1;
father[tail]:=head;
state[tail,1]:=state[head,1]+dx[k];
state[tail,2]:=state[head,2]+dy[k];
a[state[tail,1],state[tail,2]]:=1;
if (state[tail,1]=qx) and (state[tail,2]=qy)then
begin
s:=0;
last:=tail;
print(tail);
writeln(s);
tail:=0;
end;
end;
until head>=tail;
end;
begin
init;
bfs;
end.
