Submission #1124637

#	Time	Username	Problem	Language	Result	Execution time	Memory
1124637		votranngocvy	Road Construction (JOI21_road_construction)	C++20	100 / 100	1621 ms	10404 KiB

road_construction

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

#define int long long
#define pii pair<int,int>
#define fi first
#define se second

const int N = 25e4 + 5;
pii a[N];
priority_queue<int>q;
int n,k;

int dist(int i,int j) {
    return max(abs(a[i].fi - a[j].fi),abs(a[i].se - a[j].se));
}

bool check(int mid) {
    set<pii>s;
    int j = 1,cnt = 0;
    for (int i = 1; i <= n; i++) {
        while (abs(a[i].fi - a[j].fi) > mid) {
            s.erase({a[j].se,j});
            j++;
        }
        for (auto it = s.lower_bound({a[i].se - mid,-1}); it != s.end(); it++) {
            if (abs((*it).fi - a[i].se) > mid) break;
            cnt++;
            if (cnt >= k) return true;
        }
        s.insert({a[i].se,i});
    }
    return false;
}

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    cin >> n >> k;
    for (int i = 1; i <= n; i++) {
        cin >> a[i].fi >> a[i].se;
        int x = a[i].fi,y = a[i].se;
        a[i] = {x + y,x - y};
    }
    sort(a + 1,a + n + 1);
    int l = 0,r = 4e9,ans = 4e9;
    while (l <= r) {
        int mid = (l + r) / 2;
        if (check(mid)) ans = mid,r = mid - 1;
        else l = mid + 1;
    }
    set<pii>s;
    while (!q.empty()) q.pop();
    int j = 1;
    for (int i = 1; i <= n; i++) {
        while (abs(a[i].fi - a[j].fi) > ans) {
            s.erase({a[j].se,j});
            j++;
        }
        for (auto it = s.lower_bound({a[i].se - ans,-1}); it != s.end(); it++) {
            if (abs((*it).fi - a[i].se) > ans) break;
            q.push(dist(i,(*it).se));
            if (q.size() > k) q.pop();
        }
        s.insert({a[i].se,i});
    }
    vector<int>vec;
    while (!q.empty()) {
        vec.push_back(q.top());
        q.pop();
    }
    sort(vec.begin(),vec.end());
    for (auto x: vec) cout << x << "\n";
}

//Hint: xoay bảng 45 độ để chuyển khoảng cách Mahattan thành khoảng cách Cherbyshev
//(x,y) -> (x + y,x - y)

• Subtask 1: 5 / 5
• Subtask 2: 6 / 6
• Subtask 3: 7 / 7
• Subtask 4: 20 / 20
• Subtask 5: 27 / 27
• Subtask 6: 35 / 35