POJ 1258[Agri-Net]

这个是个水得不能再水的MST，可是我还WA了两次，原因如下
1.没有看到The input includes several cases.
2.把调试用的无用信息输出到了结果里（呃……脑残了）
引以为戒~~~~~

Const
        maxn=500;
Var
        codes:array[1..maxn,1..2]of longint;
        d:array[1..maxn,1..maxn]of longint;
        lowcost,pre:array[1..maxn]of longint;
        i,j,n:longint;
Procedure prim;
 var
        dist,sum,min,q,x,y:int64;
        i,j,k:longint;
 begin
        sum:=0;
        lowcost[1]:=-1;
        for i:=2 to n do
                begin
                        lowcost[i]:=d[1,i];
                        pre[i]:=1;
                end;
        for i:=1 to n-1 do
                begin
                        min:=maxlongint;
                        for k:=1 to n do
                                begin
                                        if (lowcost[k]<>-1)and(lowcost[k]<min) then
                                                begin
                                                        j:=k;
                                                        min:=lowcost[k];
                                                end;
                                end;

                        sum:=sum+min;
                        lowcost[j]:=-1;
                        for k:=1 to n do if d[j,k]<lowcost[k] then
                                begin
                                        lowcost[k]:=d[j,k];
                                        pre[k]:=j;
                                end;
                end;
        writeln(sum);
 end;
BEgin

                       while not eof do
                       begin
                        readln(n);
                        fillchar(d,sizeof(d),0);
                        for i:=1 to n do
                        begin
                                for j:=1 to n do
                                        read(d[i,j]);
                        readln;
                        end;
                        prim;
                       end;

End.