Royal Guard

    1#include <bits/stdc++.h>
    2 
    3using namespace std;
    4 
    5#define int long long 
    6 
    7signed main(){
    8    ios::sync_with_stdio(0);
    9    cin.tie(0);
    10    int n;
    11    cin >> n;
    12    unordered_map<int, vector<int>> row, col;
    13    for(int i = 0; i < n; i++){
    14        int x, y;
    15        cin >> x >> y;
    16        row[y].push_back(x); col[x].push_back(y);
    17    }  
    18    for(auto &r : row){
    19        auto &v = r.second;
    20        sort(v.begin(), v.end());
    21    }
    22    for(auto &c : col){
    23        auto &v = c.second;
    24        sort(v.begin(), v.end());
    25    }
    26    int m;
    27    cin >> m;
    28    int x, y;
    29    cin >> x >> y;
    30    int cnt = 0;
    31    for(int i = 1; i < m; i++){
    32        int nx, ny;
    33        cin >> nx >> ny;
    34        if(x == nx){ 
    35            int lo = min(ny, y), hi = max(ny, y);
    36            if(col.count(nx)){
    37                const auto &v = col[nx];
    38                cnt += upper_bound(v.begin(), v.end(), hi) - lower_bound(v.begin(), v.end(), lo);
    39            }
    40        } else { 
    41            int lo = min(nx, x), hi = max(nx, x);
    42            if(row.count(ny)){
    43                const auto &v = row[ny];
    44                cnt += upper_bound(v.begin(), v.end(), hi) - lower_bound(v.begin(), v.end(), lo);
    45            }
    46        }
    47        x = nx; y = ny;
    48    }
    49    cout << cnt << '\n';
    50    return 0;
    51}