Submission #140294

#	Time	Username	Problem	Language	Result	Execution time	Memory
140294		egorlifar	Printed Circuit Board (CEOI12_circuit)	C++17	0 / 100	44 ms	4472 KiB

circuit

/*
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 */
#include <iostream>
#include <complex>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <numeric>
#include <cstring>
#include <ctime>
#include <cstdlib>
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <list>
#include <cmath>
#include <bitset>
#include <cassert>
#include <queue>
#include <stack>
#include <deque>
#include <random>
 
using namespace std;
template<typename T1, typename T2>inline void chkmin(T1 &x, T2 y) { x = (x > y ? y: x);}
template<typename T1, typename T2>inline void chkmax(T1 &x, T2 y) { x = (x < y ? y: x);}
#define sz(c) (int)(c).size()
#define all(c) (c).begin(), (c).end()
#define rall(c) (c).rbegin(), (c).rend()
#define left left224
#define right right224
#define next next224
#define rank rank224
#define prev prev224
#define y1 y1224
#define read(FILENAME) freopen((FILENAME + ".in").c_str(), "r", stdin)
#define write(FILENAME) freopen((FILENAME + ".out").c_str(), "w", stdout)
#define files(FILENAME) read(FILENAME), write(FILENAME)
#define pb push_back
#define mp make_pair
const string FILENAME = "input";
const int MAXN = 100228;


struct point
{
    int x, y;
    int id;
    point(){}
    point(int _x, int _y) {
        x = _x;
        y = _y;
    }
};


bool good[MAXN];


point operator +(const point &a, const point &b) {
    return point(a.x + b.x, a.y + b.y);
}


point operator -(const point &a, const point &b) {
    return point(a.x - b.x, a.y - b.y);
}


long long dist(const point &a, const point &b) {
    return 1LL * (a.x - b.x) * (a.x - b.x) + 1LL * (a.y - b.y) * (a.y - b.y);
}


long long vec(const point &a, const point &b) {
    return a.x * b.y - a.y * b.x;
}


int n;
point p[MAXN], q[MAXN];
point g;


bool comp(const point &a, const point &b) {
    long long s = vec(a - g, b - g);
    if (s == 0) {
        return dist(a, g) < dist(b, g);
    }
    return s > 0;
}


int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    //read(FILENAME); 
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> p[i].x >> p[i].y;
        p[i].id = i + 1;
    }
    g = point(1e9, 1e9);
    for (int i = 0; i < n; i++) {
        if (g.y > p[i].y) {
            g = p[i];
        } else if (g.y == p[i].y) {
            if (g.x > p[i].x) {
                g = p[i];
            }
        }
    }
    sort(p, p + n, comp);
    int m = n;
    vector<int> st;
    for (int i = 0; i < n; i++) {
        if (sz(st) < 2) {
            st.pb(i);
        } else {    
            while (sz(st) >= 2 && vec(p[st.back()] - p[st[sz(st) - 2]], p[i] - p[st[sz(st) - 2]]) <= 0) {
                st.pop_back();
            }
            st.pb(i);
        }
    }
    while (sz(st) >= 2 && vec(p[st.back()] - p[st[sz(st) - 2]], p[0] - p[st[sz(st) - 2]]) <= 0) {
        st.pop_back();
    }
    for (int i = 0; i < sz(st); i++) {
        q[i] = p[st[i]];
    }
    n = sz(st);
    int uk = 0;
    int uk1 = 0;
    good[q[uk].id] = true;
    int cnt = 0;
    while (vec(q[uk], q[(uk + 1) % n]) < 0) {
        uk++;
        uk %= n;
          good[q[uk].id] = true;
        cnt++;
        if (cnt >= n) {
            break;
        }
    }
    cnt = 0;
    while (vec(q[uk1], q[(uk1 - 1 + n) % n]) > 0) {
        uk1 = (uk1 - 1 + n) % n;
        good[q[uk1].id] = true;
         cnt++;
        if (cnt >= n) {
            break;
        }
    }
    vector<int> f;
    for (int i = 1; i <= m; i++) {
        if (good[i]) {
            f.pb(i);
        }
    }
    cout << sz(f) << '\n';
    for (auto x: f) {
        cout << x << ' ';
    }
    cout << endl;
    return 0; 
}

• Subtask 1: 0 / 100