PWRFAIL - Mất điện
Tác giả: RR
Ngôn ngữ: Pascal
{$R+,Q+}
const
FINP='';
FOUT='';
MAXN=1000;
oo=1000000000;
var
c:array[1..MAXN,1..MAXN] of double;
d,x,y:array[1..MAXN] of double;
h,hpos:array[1..MAXN] of longint;
hsize,n:longint;
l:double;
function dist(x1,y1,x2,y2:double):double;
begin
dist:=sqrt(sqr(x1-x2)+sqr(y1-y2));
end;
procedure inp;
var
f:text;
i,j,u,v,m:longint;
begin
assign(f,FINP); reset(f);
read(f,n,m,l);
for i:=1 to n do read(f,x[i],y[i]);
for i:=1 to n do
for j:=1 to n do
begin
c[i,j]:=dist(x[i],y[i],x[j],y[j]);
if c[i,j]>l then c[i,j]:=oo;
end;
for i:=1 to m do
begin
read(f,u,v);
c[u,v]:=0;
c[v,u]:=0;
end;
close(f);
end;
procedure ans;
var
f:text;
begin
assign(f,FOUT); rewrite(f);
if d[n]=oo then writeln(f,-1)
else writeln(f,trunc(d[n]*1000));
close(f);
end;
procedure swap(var a,b:longint);
var
temp:longint;
begin
temp:=a; a:=b; b:=temp;
end;
procedure downHeap(i:longint);
var
j:longint;
begin
j:=i shl 1;
while (j<=hsize) do
begin
if (j<hsize) and (d[h[j+1]]<d[h[j]]) then inc(j);
if (d[h[j]]<d[h[i]]) then
begin
swap(hpos[h[i]],hpos[h[j]]);
swap(h[i],h[j]);
end;
i:=j; j:=i shl 1;
end;
end;
procedure upHeap(i:longint);
var
j:longint;
begin
j:=i shr 1;
while (i>1) and (d[h[i]]<d[h[j]]) do
begin
swap(hpos[h[i]],hpos[h[j]]);
swap(h[i],h[j]);
i:=j; j:=i shr 1;
end;
end;
procedure push(u:longint);
begin
inc(hsize); hpos[u]:=hsize; h[hsize]:=u;
upHeap(hsize);
end;
procedure pop(var u:longint);
begin
u:=h[1]; hpos[u]:=0;
swap(h[1],h[hsize]);
hpos[h[1]]:=1;
dec(hsize); downHeap(1);
end;
procedure solve;
var
u,v:longint;
begin
for u:=1 to n do d[u]:=oo;
d[1]:=0; push(1);
while hsize>0 do
begin
pop(u);
if u=n then exit;
for v:=1 to n do
if d[v]>d[u]+c[u,v] then
begin
d[v]:=d[u]+c[u,v];
if hpos[v]=0 then push(v)
else upHeap(hpos[v]);
end;
end;
end;
begin
inp;
solve;
ans;
end.