bzoj2792

首先想到二分答案是吧，设为lim

这道题难在判定，我们先不管将一个数变为0的条件

先使序列满足相邻差<=lim,这个正着扫一遍反着扫一遍即可

然后我们就要处理将一个数变为0的修改代价

当i变为0后，我们分别考虑左右两边的代价，对于左边

如果a[j]>(i-j)*lim的话，aj要变成a[i]+(i-j)*lim，否则的话，对于k<=j都不用变化，右边类似的道理

观察式子，a[j]>(i-j)*lim即a[j]+j*lim>i*lim,怎么做很明显了吧……

 var a,b,d:array[..] of longint;
     c,v:array[..] of int64;
     l,r,mx,mid,ans,i,n:longint;
     m,s:int64;

 function min(a,b:longint):longint;
   begin
     if a>b then exit(b) else exit(a);
   end;

 function max(a,b:longint):longint;
   begin
     if a>b then exit(a) else exit(b);
   end;

 function check(lim:longint):longint;
   var y,i:longint;
       s,w,t:int64;
   begin
     for i:= to n do
       b[i]:=a[i];
     t:=;
     for i:= to n- do
       if b[i+]>b[i]+lim then
       begin
         t:=t+b[i+]-(b[i]+lim);
         b[i+]:=b[i]+lim;
       end;
     for i:=n downto  do
       if b[i-]>b[i]+lim then
       begin
         t:=t+b[i-]-(b[i]+lim);
         b[i-]:=b[i]+lim;
       end;
     if t>m then exit();
     fillchar(c,sizeof(c),);
     fillchar(d,sizeof(d),);
     for i:= to n do
     begin
       y:=min(i+b[i] div lim,n);
       c[y]:=c[y]+b[i]-int64(y-i)*int64(lim);
       inc(d[y]);
       if i<> then c[i-]:=c[i-]-b[i];
       dec(d[i]);
     end;
     s:=;
     w:=;
     for i:=n downto  do
     begin
       s:=s+c[i]+w*int64(lim);
       v[i]:=s;
       w:=w+d[i];
     end;
     fillchar(c,sizeof(c),);
     fillchar(d,sizeof(d),);
     for i:=n downto  do
     begin
       y:=max(i-b[i] div lim,);
       c[y]:=c[y]+b[i]-int64(i-y)*int64(lim);
       inc(d[y]);
       c[i]:=c[i]-b[i];
       if i<> then dec(d[i-]);
     end;
     s:=;
     w:=;
     for i:= to n do
     begin
       s:=s+c[i]+w*int64(lim);
       v[i]:=v[i]+s;
       w:=w+d[i];
     end;
     for i:= to n do
       if t+v[i]<=m then exit(i);

     exit();
   end;

 begin
   readln(n,m);
   for i:= to n do
   begin
     read(a[i]);
     s:=s+a[i];
     if a[i]>mx then mx:=a[i];
   end;
   if s<=m then
   begin
     writeln('1 0');
     halt;
   end;
   l:=;
   r:=mx;
   while l<=r do
   begin
     mid:=(l+r) shr ;
     if check(mid)> then
     begin
       ans:=mid;
       r:=mid-;
     end
     else l:=mid+;
   end;
   writeln(check(ans),' ',ans);
 end.