1130B - Two Cakes - CodeForces Solution

#include<bits/stdc++.h>
using namespace std;

// Header files, namespaces, 
// macros as defined above 
#include <ext/pb_ds/assoc_container.hpp> 
#include <ext/pb_ds/tree_policy.hpp> 
using namespace __gnu_pbds; 
  
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update> 
  

#define Faster_IO ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define ll long long int
#define ull unsigned long long int
#define pii pair<int, int>
#define pll pair<ll, ll>
#define vint vector<int>
#define vlong vector<ll>
#define vchar vector<char>
#define vbool vector<bool>
#define vstring vector<string>
#define vpii vector<pair<int, int>>
#define vpll vector<pair<ll, ll>> 
#define PR_Q priority_queue
#define sz(var) (int)(var).size()
#define flf(var, start, lim_of_loop) for(ll var=start;var<=lim_of_loop;var++)
#define flr(var, start, lim_of_loop) for(ll var=start;var>=lim_of_loop;var--)
#define mset(var) memset(var, 0, sizeof(var))
#define sorting(var1, var2) sort(var1.begin() + var2, var1.end())
#define all(var1, var2) var1.begin() + var2, var1.end()
#define bitcount(var) __builtin_popcount(var)


#define here cout<<"Here"<<endl
#define haa cout<<"YES"<<endl
#define naa cout<<"NO"<<endl
#define line cout << endl;
#define nl endl
#define endl '\n'
#define sp " "
#define ff first
#define ss second
#define LB lower_bound
#define UB upper_bound
#define llmax LLONG_MAX
#define llmin LLONG_MIN
#define intmax INT_MAX
#define intmin INT_MIN
#define sstream stringstream
#define pf(var) push_front(var)
#define pb(var) push_back(var)
#define pbpr(var1, var2) push_back({var1, var2})
#define modval 1000000007
#define PI acos(-1.0)
#define eps 0.0000001 

template < typename F, typename S >ostream& operator << ( ostream& os, const pair< F, S > & p ) {return os << "(" << p.first << ", " << p.second << ")";}
template < typename T >ostream &operator << ( ostream & os, const vector< T > &v ) {os << "{";for(auto it = v.begin(); it != v.end(); ++it) {if( it != v.begin() ) os << ", ";os << *it;}return os << "}";}
template < typename T >ostream &operator << ( ostream & os, const set< T > &v ) {os << "[";for(auto it = v.begin(); it != v.end(); ++it) {if( it != v.begin() ) os << ", ";os << *it;}return os << "]";}
template < typename T >ostream &operator << ( ostream & os, const multiset< T > &v ) {os << "[";for(auto it = v.begin(); it != v.end(); ++it) {if( it != v.begin() ) os << ", ";os << *it;}return os << "]";}
template < typename F, typename S >ostream &operator << ( ostream & os, const map< F, S > &v ) {os << "[";for(auto it = v.begin(); it != v.end(); ++it) {if( it != v.begin() ) os << ", ";os << it -> first << " = " << it -> second ;}return os << "]";}
#define dbg(args...) do {cerr << #args << " : "; faltu(args); } while(0)
clock_t tStart = clock();
#define timeStamp dbg("Execution Time: ", (double)(clock() - tStart)/CLOCKS_PER_SEC)
void faltu () {cerr << endl;}
template <typename T>void faltu( T a[], int n ) {for(int i = 0; i < n; ++i) cerr << a[i] << ' ';cerr << endl;}
template <typename T, typename ... hello>void faltu( T arg, const hello &... rest) {cerr << arg << ' ';faltu(rest...);}

bool CMP(pair<ll, ll> &a, pair<ll, ll> &b){
	if(a.ff > b.ff){
		return 1;
	}
	else if(a.ff == b.ff){
		if(a.ss < b.ss){
			return 1;
		}
		else{
			return 0;
		}
	}
	else{
		return 0;
	}
}

bool SPACE(char ch){if(ch == ' '){return true;}else{return false;}}
bool PALINDROME(string s, int sz){for(int i=1, j=sz;i<=(sz/2);i++, j--){if(s[i] != s[j]){return false;}}return true;}
bool PRIME(ll n){if(n < 2){return false;}if(n == 2){return true;}for(ll ii = 2; ii * ii <= n; ii++){if(n % ii == 0){return false;}}return true;}


ll LEN(ll x){ll res=0;while(x!=0){res++;x/=10;}return res;}
ll CEIL(ll n, ll x){if(n % x == 0){return (n / x);}else{return ((n / x) + 1);}}
ll GCD(ll a, ll b){if (b == 0){return a;}return GCD(b, a % b);}
ll LCM(ll a, ll b){return (a / GCD(a, b)) * b;}
ll FACTORIAL(ll a){if(a == 0 || a == 1){return 1;}else{return a * FACTORIAL(a - 1);}}
ll COMBINATION(ll n, ll r){ll res = 0;if (r == 0) {return 1;}else{res = COMBINATION(n, r - 1) * (n - r + 1) / r;}return res;}
ll SOD(ll x){ll res = 0;while(x != 0){res += (x % 10); x /= 10;}return res;}
ll SUBSTRACT(ll a, ll b, ll mod){return (a%mod-b%mod+mod)%mod;}

/// Base Changer ///
char reVal(ll num){if (num >= 0 && num <= 9){return (char)(num + '0');}else{return (char)(num - 10 + 'A');}}
string BASE_CHANGER(ll inputNum, ll base){ll index = 0;string res = "";while (inputNum > 0) {res.push_back(reVal(inputNum % base));index++;inputNum /= base;}reverse(res.begin(), res.end());return res;}

void STACK_Show(stack<int> temp){while(!temp.empty()){cout << temp.top() << sp; temp.pop();}cout << endl;}

void Q_Show(queue<int> temp){while(!temp.empty()){cout << temp.front() << sp; temp.pop();}cout << endl;}
void DQ_Show(deque<int> temp){while(!temp.empty()){cout << temp.front() << sp; temp.pop_front();}cout << endl;}
void PRQ_SHOW(PR_Q<ll> temp){while(!temp.empty()){cout << temp.top() << sp; temp.pop();}cout << endl;}

void Q_Pair_Show(queue<pii>temp){while(!temp.empty()){cout << temp.front().ff << sp << temp.front().ss << endl;temp.pop();}}
void PRQ_Pair_Show(PR_Q<pll, vector<pll>, greater<pll>> temp){while(!temp.empty()){cout << temp.top().ff << sp << temp.top().ss << endl;temp.pop();}cout << endl;}


int dx[]  = {  1, -1,  0,  0,  1, -1,  1, -1};
int dy[]  = {  0,  0,  1, -1,  1, -1, -1,  1};
int knx[] = { -2, -2,  2,  2, -1,  1, -1,  1};
int kny[] = { -1,  1, -1,  1, -2, -2,  2,  2};



vector<vector<ll>> g;
vector<ll> par, need, dp;
vector<char> dir;
vector<bool> vis;

void solve(){
	ll n; cin >> n;

	vlong arr(2 * n);

	vpll vpr(n + 1, {-10, -10});

	for(int i = 0; i < 2 * n; i++){
		cin >> arr[i];

		if(vpr[arr[i]].ff == -10){
			vpr[arr[i]].ff = i;
		}
		else{
			vpr[arr[i]].ss = i;
		}
	}

	pll cur = {0, 0};

	ll ans = 0;

	for(int i = 1; i <= n; i++){
		ll dis1 = abs(cur.ff - vpr[i].ff) + abs(cur.ss - vpr[i].ss);
		ll dis2 = abs(cur.ff - vpr[i].ss) + abs(cur.ss - vpr[i].ff);

		if(dis1 <= dis2){
			ans += dis1;
		}
		else{
			ans += dis2;
		}

		cur = vpr[i];
	}

	cout << ans << endl;

}


int main ()
{
	Faster_IO;
	int tc; tc = 1;
	// int tc; cin >> tc;
	// cout << tc << endl;
	flf(iii, 1, tc){
		// cout << "Case " << iii << ": " << endl;
		solve();
	}
}