Lasers and Mirrors

#include <iostream>
#include <string>
#include <algorithm>
#include <cmath>
#include <vector>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <deque>
#include <unordered_map>
#include <numeric>
#include <iomanip>
using namespace std;
#define pii pair<int, int>
#define FAST ios_base::sync_with_stdio(false); cin.tie(NULL)
const int dx[4] = {0, 1, 0, -1}, dy[4] = {1, 0, -1, 0};
const int MOD = 1e9;
const int MAX = 100005;

int n;
pii laser, barn;
vector<pii> mirror;
vector<int> x_comp, y_comp;
vector<int> coords[MAX][2]; // 0 = x, 1 = y
int visitedx[MAX][2], visitedy[MAX][2];

struct vertex{
    int x, y, dir, dist;
    void print(){
        cout << "Pushed to queue: " << x << " " << y << " " << dir << " " << dist << "\n";
    }
};

int main() {
    FAST;
    freopen("lasers.in", "r", stdin);
    freopen("lasers.out", "w", stdout);
    cin >> n >> laser.first >> laser.second >> barn.first >> barn.second;
    mirror.resize(n + 2);
    for(int i = 0; i < n + 2; i++){
        if(i == n){
            mirror[i] = laser;
        }
        else if(i == n + 1){
            mirror[i] = barn;
        }
        else{
            cin >> mirror[i].first >> mirror[i].second;
        }
        x_comp.push_back(mirror[i].first); y_comp.push_back(mirror[i].second);
    }
    // Coordinate Compression
    sort( x_comp.begin(), x_comp.end() );
    x_comp.erase( unique( x_comp.begin(), x_comp.end() ), x_comp.end() );
    sort( y_comp.begin(), y_comp.end() );
    y_comp.erase( unique( y_comp.begin(), y_comp.end() ), y_comp.end() );
    for(int i = 0; i < n + 2; i++){
        mirror[i].first = (int)(lower_bound(x_comp.begin(), x_comp.end(), mirror[i].first) - x_comp.begin());
        mirror[i].second = (int)(lower_bound(y_comp.begin(), y_comp.end(), mirror[i].second) - y_comp.begin());
        // cout << mirror[i].first << " " << mirror[i].second << "\n";
        coords[mirror[i].second][0].push_back(mirror[i].first);
        coords[mirror[i].first][1].push_back(mirror[i].second);
    }
    laser = mirror[n];
    barn = mirror[n + 1];
    queue<vertex> q;
    vertex init;
    init.x = laser.first;
    init.y = laser.second;
    init.dir = 0;
    init.dist = 0;
    vertex init2 = init;
    init2.dir = 1;
    q.push(init);
    q.push(init2);
    int ans = 2e9;
    while(!q.empty()){
        vertex cur = q.front();
        q.pop();
        int curx = cur.x, cury = cur.y, cur_dir = cur.dir, cur_dist = cur.dist;
        // cout << "BFS: " << curx << " " << cury << " " << cur_dir << " " << cur_dist << "\n";
        if(!(curx == laser.first and cury == laser.second)){
            visitedx[curx][cur_dir] = 1;
            visitedy[cury][cur_dir] = 1;
        }
        if(curx == barn.first or cury == barn.second){
            ans = min(ans, cur_dist);
        }
        if(cur_dir == 0){
            for(auto nxtx: coords[cury][cur_dir]){
                vertex nxt;
                nxt.x = nxtx;
                nxt.y = cury;
                nxt.dir = 1 - cur_dir;
                nxt.dist = cur_dist + 1;
                if(visitedx[nxt.x][nxt.dir] == 0 and visitedy[nxt.y][nxt.dir] == 0 and !(nxt.x == laser.first and nxt.y == laser.second)){
                    q.push(nxt);
                    // nxt.print();
                }
            }
        }
        else{
            for(auto nxty: coords[curx][cur_dir]){
                vertex nxt;
                nxt.x = curx;
                nxt.y = nxty;
                nxt.dir = 1 - cur_dir;
                nxt.dist = cur_dist + 1;
                if(visitedx[nxt.x][nxt.dir] == 0 and visitedy[nxt.y][nxt.dir] == 0 and !(nxt.x == laser.first and nxt.y == laser.second)){
                    q.push(nxt);
                    // nxt.print();
                }
            }
        }
    }
    if(ans == 2e9){
        cout << "-1\n";
    }
    else{
        cout << ans;
    }
}