Submission #409908

#	Time	Username	Problem	Language	Result	Execution time	Memory
409908		Victor	Triangles (CEOI18_tri)	C++17	100 / 100	193 ms	2500 KiB

tri

#include <bits/stdc++.h>

#include "trilib.h"

using namespace std;

#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define per(i, a, b) for (int i = b - 1; i >= (a); --i)
#define trav(a, x) for (auto &a : x)

#define all(x) x.begin(), x.end()
#define sz(x) x.size()
#define pb push_back

#define umap unordered_map
#define uset unordered_set

typedef pair<int, int> ii;
typedef pair<int, ii> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<vi> vvi;
typedef long long ll;

const int INF = 1000000007;

int main() {
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);

    bitset<40001> taken;
    const int n = get_n();
    int start = 1, q = 1, ans = 0;
    vi cities, hull;
    bool stop = 0;
    int x = 10;

    rep(i,1,n+1)cities.pb(i);

    while (x--) {
        vi sorted;
        trav(city,cities) {
            int lo = 0, hi = sz(sorted);
            if (city == start) continue;

            while (lo != hi) {
                if (1'000'000 == q++) {
                    stop = 1;
                    break;
                }

                int mid = (lo + hi) >> 1;
                if (is_clockwise(start, sorted[mid], city))
                    hi = mid;
                else
                    lo = mid + 1;
            }

            if (stop) break;
            sorted.insert(sorted.begin() + lo, city);
        }

        if (stop) break;

        cities.swap(sorted);
        int i = 1;
        hull.pb(start);
        hull.pb(cities[0]);

        while (i < sz(cities)) {
            int j = sz(hull) - 1;

            if (1'000'000 == q++) {
                stop = 1;
                break;
            }

            if (is_clockwise(hull[j - 1], hull[j], cities[i]))
                hull.pop_back();
            else
                hull.pb(cities[i++]);
        }

        if (stop) break;

        ans = sz(hull);
        start = hull[random() % ans];
        cities.swap(hull);
        hull.clear();
    }

    give_answer(ans);
    return 0;
}

Compilation message (stderr)

tri.cpp: In function 'int main()':
tri.cpp:70:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   70 |         while (i < sz(cities)) {
      |                  ^

• Subtask 1: 15 / 15
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 20 / 20
• Subtask 5: 25 / 25