【codevs2211】WJM2BMR安慰MM记 区间dp

var
        n,c,i,j,sum:longint;
        m,w:array[0..1100] of longint;
        a,l,r:array[0..1005,0..1005] of longint;
                                           
        function min(a,b:longint):longint;
        begin
                if a<b then exit(a) else exit(b);
        end;

        begin
                readln(n,c);
                sum:=0;
                for i:=1 to n do
                begin
                        readln(m[i],w[i]);
                        inc(sum,w[i]);
                end;

        for i:=1 to n do
        begin
                a[i,i]:=sum-w[i];
                for j:=i+1 to n do a[i,j]:=a[i,j-1]-w[j];
        end;

        for i:=c+1 to n do
        begin
                r[c,i]:=r[c,i-1]+(m[i]-m[i-1])*a[c,i-1];
                l[c,i]:=r[c,i]+(m[i]-m[c])*a[c,i];
        end;

        for i:=c-1 downto 1 do
        begin
                l[i,c]:=l[i+1,c]+(m[i+1]-m[i])*a[i+1,c];
                r[i,c]:=l[i,c]+(m[c]-m[i])*a[i,c];
        end;

        for i:=c-1 downto 1 do
        for j:=c+1 to n do
        begin
                r[i,j]:=min(r[i,j-1]+(m[j]-m[j-1])*a[i,j-1],l[i,j-1]+(m[j]-m[i])*a[i,j-1]);
                l[i,j]:=min(l[i+1,j]+(m[i+1]-m[i])*a[i+1,j],r[i+1,j]+(m[j]-m[i])*a[i+1,j]);
        end;

        writeln(min(l[1,n],r[1,n]));

        end.