所求的Z序列为6,7,8,13,14,15,18.
R=13

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<cstring>
using namespace std;
int read()
{int x=0,f=1; char ch=getchar();while (ch<'0' || ch>'9') {if (ch=='-') f=-1; ch=getchar();}while (ch>='0' && ch<='9') {x=x*10+ch-'0'; ch=getchar();}return x*f;
}
#define maxn 1000100
long long ans;
int n,data[maxn],root[maxn],L[maxn],R[maxn],cnt[maxn],tot;
struct LeftTreeNode
{int sz,son[maxn][2],d[maxn],size[maxn],a[maxn];
//    LeftTreeNode ()
//        {
//            sz=0;memset(son,0,sizeof(son));memset(size,0,sizeof(size));
//            memset(cnt,0,sizeof(cnt));memset(a,0,sizeof(a));memset(d,0,sizeof(d));
//        }int Merge(int x,int y){if (!x) return y;if (!y) return x;if (a[x]<a[y]) swap(x,y);son[x][1]=Merge(son[x][1],y);size[x]=size[son[x][0]]+size[son[x][1]]+1;if (d[son[x][1]]>d[son[x][0]]) swap(son[x][0],son[x][1]);d[x]=d[son[x][1]]+1;return x;}int Push(int x){a[++sz]=x; size[sz]=1;son[sz][0]=son[sz][1]=d[sz]=0;return sz;}int Pop(int x) {return Merge(son[x][0],son[x][1]);}int Top(int x) {return a[x];}int Size(int x) {return size[x];}
}LTHeap;
int main()
{n=read();for (int i=1; i<=n; i++) data[i]=read()-i;for (int i=1; i<=n; i++){tot++;root[tot]=LTHeap.Push(data[i]); cnt[tot]=1; L[tot]=R[tot]=i;while (tot>1 && LTHeap.Top(root[tot])<LTHeap.Top(root[tot-1])){tot--;root[tot]=LTHeap.Merge(root[tot],root[tot+1]); cnt[tot]+=cnt[tot+1]; R[tot]=R[tot+1];while (LTHeap.Size(root[tot])*2>cnt[tot]+1) root[tot]=LTHeap.Pop(root[tot]);}}for (int i=1; i<=tot; i++)for (int j=L[i],top=LTHeap.Top(root[i]); j<=R[i]; j++)ans+=abs(data[j]-top);printf("%lld\n",ans);return 0;
}