筷子

题面：

 

思路：

        DP，f[i,j]表示到i点取j双的最优值

代码：

 

var n,k,i,j:longint;
 f:Array[0..1005,0..1005] of longint;
  a:array[0..1005] of longint;

    procedure sort(l,r: longint);
      var
         i,j,x,y: longint;
      begin
         i:=l;
         j:=r;
         x:=a[(l+r) div 2];
         repeat
           while a[i]<x do
            inc(i);
           while x<a[j] do
            dec(j);
           if not(i>j) then
             begin
                y:=a[i];
                a[i]:=a[j];
                a[j]:=y;
                inc(i);
                j:=j-1;
             end;
         until i>j;
         if l<j then
           sort(l,j);
         if i<r then
           sort(i,r);
      end;


function min(x,y:longint):longint;
begin
 if x<y then exit(x) else exit(y);
end;

begin


assign(input,'chop.in');
reset(input);
assign(output,'chop.out');
rewrite(output);

read(n,k);
inc(k,3);
if n<k*2 then begin writeln(-1); exit; end;

for i:=1 to n do
 read(a[i]);

sort(1,n);

fillchar(f,sizeof(f),127);
f[0,0]:=0;

for i:=2 to n do
 for j:=1 to k do
  f[i,j]:=min(f[i-1,j],f[i-2,j-1]+sqr(a[i]-a[i-1]));


writeln(f[n,k]);


close(input);close(output);
end.