Yet another 2D Walking 1066/F

/// http://codeforces.com/problemset/problem/1066/F - 18/10/18

#include <iostream>
#include <map>
#include <vector>
#include <algorithm>

#define f first
#define s second

#define cx f
#define cy s
#define ll long long

using namespace std;

map <int, int> mapa;

int DarId (int num)
{
    if ( !mapa[num] )
        mapa[num] = mapa.size();
    return mapa[num];
}

ll Dist( const pair<int, int> *A, const pair <int, int> *B )
{
    return abs(A->cx - B->cx) + abs(A->cy - B->cy);
}

int main()
{
    int n;
    cin>>n;

    vector< pair<int, pair<int, int> > > ving (n);

    int x, y;
    for (int i=0; i<n; i++)
    {
        cin >> x >> y;

        ving[i].s.cx = x;
        ving[i].s.cy = y;
        ving[i].f = max (x, y);
    }
    sort( ving.begin(), ving.end() );

    vector < pair< pair<int,int> , pair<int,int> > > v (2*100005);
    v[0] = { {0,0}, {0,0} };

    int id;
    for (int i=0; i<n; i++)
    {
        pair <int, int> cord = ving[i].s;

        id = DarId( max(cord.cx, cord.cy) );

        pair <int, int> A = v[id].f;
        pair <int, int> B = v[id].s;

        if ( !A.cx && !A.cy )                        ///me guardo el punto de ese nivel que esté mas mas cerca de la derecha (menor X)
            A = cord;
        else if ( cord.cx < A.cx )
            A = cord;
        else if (( cord.cx == A.cx ) && ( cord.cy > A.cy ))
            A = cord;

        if ( !B.cx && !B.cy )                        ///me guardo el punto de ese nivel que esté mas mas cerca de abajo (menor Y)
            B = cord;
        else if ( cord.cy < B.cy )
            B = cord;
        else if (( cord.cy == B.cy ) && ( cord.cx > B.cx ))
            B = cord;

        v[id].f  = A;
        v[id].s = B;
    }

    v.resize( 1+mapa.size() );

    ll ant_CtA =0, ant_CtB=0;
    ll CtA =0, CtB=0;

    for ( id=1; id<v.size(); id++)
    {
        pair<int,int> *A = &v[id].f;
        pair<int,int> *B = &v[id].s;

        pair<int,int> *ant_A = &v[id-1].f;
        pair<int,int> *ant_B = &v[id-1].s;

        CtA = Dist(A, B) + min( ant_CtA + Dist(ant_B, A) , ant_CtB + Dist(ant_A, A) );
        CtB = Dist(A, B) + min( ant_CtA + Dist(ant_B, B) , ant_CtB + Dist(ant_A, B) );

        ant_CtA = CtA;
        ant_CtB = CtB;
    }
    cout<<min(ant_CtA, ant_CtB);

    return 0;
}