bzoj1367 [Baltic2004]sequence

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<iostream>
#define fo(i,a,b) for(int i=a;i<=b;i++)
#define fd(i,a,b) for(int i=a;i>=b;i--)
using namespace std;
const int N=1e6+5;
typedef long long ll;
int n,m;
int a
,tot=0;
int v
,tr
[2],dist
,siz
;
int root
,l
,r
;

inline int merge(int x,int y)
{
if (!x||!y)return x+y;
if (v[x]<v[y])swap(x,y);
tr[x][1]=merge(tr[x][1],y);
siz[x]=siz[tr[x][0]]+siz[tr[x][1]]+1;
if (dist[tr[x][1]]>dist[tr[x][0]])swap(tr[x][0],tr[x][1]);
dist[x]=dist[tr[x][1]]+1;
return x;
}

inline void pop(int &x)
{
x=merge(tr[x][0],tr[x][1]);
}
inline int newnode(int x)
{
v[++tot]=x;
siz[tot]=1;
tr[tot][0]=tr[tot][1]=dist[tot]=0;
return tot;
}
int main()
{
scanf("%d",&n);
fo(i,1,n)
{
scanf("%d",&a[i]);
a[i]-=i;
}
int cnt=0;
fo(i,1,n)
{
cnt++;
root[cnt]=newnode(a[i]);
l[cnt]=r[cnt]=i;
while (cnt>1&&v[root[cnt]]<v[root[cnt-1]])
{
cnt--;
root[cnt]=merge(root[cnt],root[cnt+1]);
r[cnt]=r[cnt+1];
while (siz[root[cnt]]*2>r[cnt]-l[cnt]+2)pop(root[cnt]);
}
}
ll ans=0;
fo(i,1,cnt)
{
int t=v[root[i]];
fo(j,l[i],r[i])ans+=abs(t-a[j]);
}
printf("%lld\n",ans);
return 0;
}