codevs2011最小距离之和 [2013年省队选拔赛辽宁]

var a:array[0..210,0..210]of longint;
  x,y,z,ans:array[0..210]of longint;
  n,m,i,j,k:longint;
  b:boolean;
begin
  read(n);
  for i:=1 to n do
    for j:=1 to n do
      read(a[i,j]);//读入图
  read(m);
  for i:=1 to m do begin
    read(x[i],y[i]); z[i]:=a[x[i],y[i]];
    a[x[i],y[i]]:=1<<29;//删边
  end;
  for k:=1 to n do
    for i:=1 to n do
      for j:=1 to n do
        if a[i,j]>a[i,k]+a[k,j] then a[i,j]:=a[i,k]+a[k,j];//跑Floyd
  for i:=m downto 1 do begin
    ans[i]:=0; b:=false;
    for j:=1 to n do begin
      for k:=1 to n do begin
        if a[j,k]>=1<<29 then begin
          ans[i]:=-1; b:=true; break;
        end;
        ans[i]:=ans[i]+a[j,k];
      end;
      if b then break;
    end;//算距离之和
    for j:=1 to n do
      for k:=1 to n do
        if a[j,k]>a[j,x[i]]+z[i]+a[y[i],k] then a[j,k]:=a[j,x[i]]+z[i]+a[y[i],k];//加边，更新答案
  end;
  for i:=1 to m do
    if ans[i]=-1 then writeln(‘INF‘)
    else writeln(ans[i]);//输出答案
end.