CODEVS1079 回家 （最短路）

　　真是语死早，题目看了两遍才看懂。

　　按照题目要求建边，从‘Z‘开始跑最短路即可。

Program CODEVS1079;
var a:array[0..1000,0..1000] of longint;
    d:array[0..1000] of longint;
    pd:array[0..1000] of boolean;
    flag:array[0..1000] of boolean;
    b:array[0..10000] of longint;
    ch,space,ch2,ans:char;
    i,j,m,x,min:longint;
procedure spfa(s:longint);
var i,j,l,r,u,v:longint;
begin
  fillchar(pd,sizeof(pd),false);
  fillchar(b,sizeof(b),0);
  fillchar(d,sizeof(d),$7f);
  l:=1; r:=1; pd[s]:=true; b[l]:=s; d[s]:=0;
  while l<=r do
    begin
      u:=b[l];
      for v:=ord(‘A‘) to ord(‘z‘) do
        if (a[u,v]<10000) and (d[u]+a[u,v]<d[v]) then
          begin
            d[v]:=d[u]+a[u,v];
            if not pd[v] then
              begin
                inc(r);
                b[r]:=v;
                pd[v]:=true;
              end;
          end;
      inc(l);
      pd[u]:=false;
    end;
end;
begin
  fillchar(flag,sizeof(flag),false);
  fillchar(a,sizeof(a),$7f);
  readln(m);
  for i:=1 to m do
    begin
      readln(ch,space,ch2,space,x);
      if x>a[ord(ch),ord(ch2)] then continue;
      a[ord(ch),ord(ch2)]:=x;
      a[ord(ch2),ord(ch)]:=x;
      flag[ord(ch)]:=true;
      flag[ord(ch2)]:=true;
    end;
    min:=maxlongint;
  spfa(ord(‘Z‘));
  for i:=ord(‘A‘) to ord(‘Y‘) do
    if flag[i] then
      if d[i]<min then
        begin
          ans:=chr(i);
          min:=d[i];
        end;
  writeln(ans,‘ ‘,min);
end.