优化过的:
var a:array[1..100,1..100]of longint;
b:array[1..100,0..100]of longint;
f:array[1..1000]of longint;
d:array[1..100]of longint;
v:array[1..100]of boolean;
i,j,aa,bb,x,y,now,s,t,n,p:longint;
begin
readln(n,p);
for i:=1 to p do
begin
for j:=1 to p do
a[i,j]:=maxlongint shr 2;
d[i]:=maxlongint shr 2;
a[i,i]:=0;
end;
for i:=1 to n do
begin
readln(x,y,a[x,y]);
a[y,x]:=a[x,y];
b[x,0]:=b[x,0]+1;
b[x,b[x,0]]:=y;
b[y,0]:=b[y,0]+1;
b[y,b[y,0]]:=x;
end;
readln(s,t);
aa:=1;
bb:=1;
d[s]:=0;
f[1]:=s;
v[s]:=true;
while aa<=bb do
begin
now:=f[aa];
for i:=1 to b[now,0] do
begin
if d[b[now,i]]>d[now]+a[now,b[now,i]] then
begin
d[b[now,i]]:=d[now]+a[now,b[now,i]];
if not v[b[now,i]] then
begin
bb:=bb+1;
f[bb]:=b[now,i];
v[b[now,i]]:=true;
end;
end;
end;
v[now]:=false;
aa:=aa+1;
end;
writeln(d[t]);
end.

前向星优化
var
a,b,e:array[1..1000]of longint;
vis:array[1..2000]of boolean;
q,d,f:array[1..2001]of longint;
n,m,i,s,t:longint;
procedure qsort(l,r:longint);
var i,j,x,y:longint;
begin
i:=l;
j:=r;
x:=a[(l+r) shr 1];
repeat
while a[i]<x do inc(i);
while a[j]>x do dec(j);
if not (i>j) then
begin
y:=a[i];
a[i]:=a[j];
a[j]:=y;
y:=b[i];
b[i]:=b[j];
b[j]:=y;
y:=e[i];
e[i]:=e[j];
e[j]:=y;
inc(i);
dec(j);
end;
until i>j;
if i<r then qsort(i,r);
if l<j then qsort(l,j);
end;
procedure spfa(s:longint);
var i,k,l,t:longint;
begin
fillchar(vis,sizeof(vis),false);
for i:=1 to n do
d[i]:=maxlongint;
d[s]:=0;
l:=0;
t:=1;
q[1]:=s;
vis[s]:=true;
repeat
l:=l mod 10000+1;
k:=q[l];
for i:=f[k] to f[k+1]-1 do
if d[k]+e[i]<d[b[i]] then
begin
d[b[i]]:=d[k]+e[i];
if not vis[b[i]] then
begin
t:=t mod 10000+1;
q[t]:=b[i];
vis[b[i]]:=true;
end;
end;
vis[k]:=false;
until l=t;
end;
begin
readln(n,m);
for i:=1 to m do
readln(a[i],b[i],e[i]);
qsort(1,m);
for i:=1 to m do
if f[a[i]]=0 then
f[a[i]]:=i;
f[n+1]:=m+1;
for i:=n downto 1 do
if f[i]=0 then
f[i]:=f[i+1];
readln(s,t);
spfa(s);
writeln(d[t]);
end.

顶起来！！

为啥我以前起的变量名都是这样的！！？！？！？！？！？！