# ROS Study Notes Report Error (1): Publisher and Subscriper&#8217;s programming implementation error solution

2023-01-30

``This question is still simple, you can be AC with a deep search+memory!``
``````   var
way:array[1..4,1..2] of longint=((1,0),(0,1),(-1,0),(0,-1));
a,zx:array[0..101,0..101] of longint;
m,n,i,j,x,y,k,ans:longint;
procedure dg(x,y,s:longint);
var
i,j,xx,yy,x2,y2:longint;
begin
if s>=zx[x,y] then exit
else zx[x,y]:=s;
if (x=m) and (y=m) then
begin
if ans>s then ans:=s;
exit;
end;
for i:=1 to 4 do
begin
xx:=x+way[i,1];
yy:=y+way[i,2];
if (xx>=1) and (yy>=1) and (xx<=m) and (yy<=m) then
begin
if a[xx,yy]=maxlongint then
begin
if (xx=m) and (yy=m) then dg(xx,yy,s+2);
for j:=1 to 4 do
begin
x2:=xx+way[j,1];
y2:=yy+way[j,2];
if (x2>=1) and (y2>=1) and (x2<=m) and (y2<=m) then
begin
if a[x2,y2]<>maxlongint then
begin
if a[x2,y2]<>a[x,y] then dg(x2,y2,s+3)
else dg(x2,y2,s+2);
end;
end;
end;
end else if a[x,y]<>a[xx,yy] then dg(xx,yy,s+1)
else dg(xx,yy,s);
end;
end;
end;
begin
assign(input,'chess.in');reset(input);
assign(output,'chess.out');rewrite(output);
for i:=0 to 101 do
for j:=0 to 101 do
begin
a[i,j]:=maxlongint;
zx[i,j]:=maxlongint;
end;
for i:=1 to n do
begin
a[x,y]:=k;
end;
ans:=maxlongint;
dg(1,1,0);
if ans=maxlongint then writeln(-1)
else writeln(ans);
close(input);
close(output);
end.
``````

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