https://codeforces.com/contest/1130/problem/B

题解：

/*
*@Author:   STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG
#define RI register int
using namespace std;
typedef long long ll;
//typedef __int128 lll;
const int N=200000+10;
const int MOD=1e9+7;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const int INF = 0x3f3f3f3f;
int t,n,m,k,q;
int ans,cnt,flag,temp;
ll d[N];
struct node {

    int id,a;
    bool operator <(const node &S)const{
        return a<S.a;
    }
}e[N];
char str;
int main()
{
#ifdef DEBUG
	freopen("input.in", "r", stdin);
	//freopen("output.out", "w", stdout);
#endif
       scanf("%d",&n);
    for(int i=1;i<=2*n;i++){
        scanf("%d",&e[i].a);
        e[i].id=i;
    }
    //scanf("%d",&t);
    //while(t--){}
    sort(e+1,e+2*n+1);
    int x=1,y=1;
    for(int i=1;i<=n;i++){
        if(abs(x-e[i*2-1].id)+abs(y-e[i*2].id)<=abs(y-e[i*2-1].id)+abs(x-e[i*2].id)){
            d[i]=d[i-1]+abs(x-e[i*2-1].id)+abs(y-e[i*2].id);
            x=e[i*2-1].id;
            y=e[i*2].id;
        }else{
            d[i]=d[i-1]+abs(y-e[i*2-1].id)+abs(x-e[i*2].id);
            x=e[i*2].id;
            y=e[i*2-1].id;
        }
    }
    cout << d[n] << endl;
    //cout << "Hello world!" << endl;
    return 0;
}