HDu 4262セグメントツリー最適化

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;

#define lson u<<1
#define rson u<<1|1
#define MAXN 100005

int map[MAXN];

struct Node{
	int lef,rig;
	int sum;
}T[MAXN<<2];

void PushUp(int u){
	T[u].sum=T[lson].sum+T[rson].sum;
}

void Build(int u,int l,int r){
	T[u].lef=l;
	T[u].rig=r;
	if(l==r){T[u].sum=1;return;}
	int mid=(l+r)>>1;
	Build(lson,l,mid);
	Build(rson,mid+1,r);
	PushUp(u);
}

void Update(int u,int pos,int val){
	if(T[u].lef==T[u].rig){T[u].sum=val;return;}
	if(pos<=T[lson].rig)Update(lson,pos,val);
	else Update(rson,pos,val);
	PushUp(u);
}

int Query(int u,int l,int r){
		if(l<=T[u].lef&&T[u].rig<=r)return T[u].sum;
		if(r<=T[lson].rig)return Query(lson,l,r);
		if(l>=T[rson].lef)return Query(rson,l,r);
		return Query(lson,l,T[lson].rig)+Query(rson,T[rson].lef,r);

}

int main(){
	int n;
	while(scanf("%d",&n)&&n){
		int tmp;
		for(int i=1;i<=n;i++){
			scanf("%d",&tmp);
			map[tmp]=i;
		}
		Build(1,1,n);

		int cur=1;
		__int64 ans=n;

		for(int i=1;i<n;i++){
			if(i==1)tmp=Query(1,cur,map[i])-1;
			else if(map[i]>cur)tmp=Query(1,cur+1,map[i])-1;
			else tmp=Query(1,map[i],cur-1);
			ans+=min(tmp,n-i+1-tmp);
			Update(1,map[i],0);
			cur=map[i];
		}
		printf("%I64d
",ans);
	}
	return 0;
}