bzoj 1601 最小生成树

原题传送门http://www.lydsy.com/JudgeOnline/problem.php?id=1601

最小生成树的比较水的题，我们只需要加一个源点，连向所有的点，边权为每个点建水库的代价

/**************************************************************

    Problem: 1601

    User: BLADEVIL

    Language: Pascal

    Result: Accepted

    Time:216 ms

    Memory:3744 kb

****************************************************************/

 

//By BLADEVIL

var

    n                       :longint;

    pre, other, len         :array[0..300020] of longint;

    tot                     :longint;

    father                  :array[0..500] of longint;

    ans                     :longint;

     

procedure swap(var  a,b:longint); 

var

    c                       :longint;

begin

    c:=a; a:=b; b:=c;

end;

     

procedure qs(low,high:longint);

var

    i, j, x                 :longint;

begin

    i:=low; j:=high; x:=len[(i+j) div 2];

    while i<j do

    begin

        while len[i]<x do inc(i);

        while len[j]>x do dec(j);

        if i<=j then

        begin

            swap(len[i],len[j]);

            swap(pre[i],pre[j]);

            swap(other[i],other[j]);

            inc(i); dec(j);

        end;

    end;

    if i<high then qs(i,high);

    if j>low then qs(low,j);

end;

     

     

procedure init;

var

    i, j                    :longint;

    x                       :longint;

     

begin

    read(n);

    for i:=1 to n do

    begin

        inc(tot);

        pre[tot]:=n+1;

        other[tot]:=i;

        read(len[tot]);

    end;

    for i:=1 to n do

        for j:=1 to n do

        if i<>j then

        begin

            inc(tot);

            pre[tot]:=i;

            other[tot]:=j;

            read(len[tot]);

        end else read(x);

    qs(1,tot);

end;

 

function getfather(x:longint):longint;

begin

    if father[x]=x then exit(x);

    father[x]:=getfather(father[x]);

    exit(father[x]);

end;

 

procedure main;

var

    i                       :longint;

    x, y, fx, fy            :longint;

     

begin

    for i:=1 to n+1 do father[i]:=i;

    for i:=1 to tot do

    begin

        x:=pre[i]; y:=other[i];

        fx:=getfather(x);

        fy:=getfather(y);

        if fx<>fy then

        begin

            inc(ans,len[i]);

            father[fx]:=fy;

        end;

    end;

    writeln(ans);

end;

 

begin

    init;

    main;

end.