Submission #95194

#	Time	Username	Problem	Language	Result	Execution time	Memory
95194		win11905	Lightning Rod (NOI18_lightningrod)	C++11	66 / 100	2072 ms	131908 KiB

Main

/**
 * code generated by JHelper
 * More info: https://github.com/AlexeyDmitriev/JHelper
 * @author win11905
 */

#include <bits/stdc++.h>
#define all(x) (x).begin(), (x).end()
#define vi vector<int>
#define iii tuple<int, int, int>
#define long long long
#define pii pair<int, int>
#define x first
#define y second
using namespace std;
const long MOD = 1e9+7, LINF = 1e18 + 1e16;
const int INF = 1e9+1;
const double EPS = 1e-10;
const int dx[4] = {-1, 0, 1, 0}, dy[4] = {0, 1, 0, -1};


class lightningrod {
private:
    int n;
    stack<pii> stk;
    bool check_cover(pii a, pii b) {
        return abs(a.x - b.x) <= a.y - b.y;
    }
public:
    void solve(istream& cin, ostream& cout) {
        scanf("%d", &n);
        vector<pii> vec;
        for(int i = 0, a, b; i < n; ++i) {
            scanf("%d %d", &a, &b);
            vec.emplace_back(a, b);
        }
        sort(vec.begin(), vec.end(), [&](const pii &a, const pii &b) {
            if(a.x == b.x) return a.y > b.y;
            return a.x < b.x;
        });
        for(auto v : vec) {
            if(stk.empty()) {
                stk.emplace(v);
                continue;
            }
            if(check_cover(stk.top(), v)) continue;
            while(!stk.empty() && check_cover(v, stk.top())) stk.pop();
            stk.emplace(v);
        }
        printf("%d\n", (int)stk.size());
    }
};

class Solver {
public:
    void solve(std::istream& in, std::ostream& out) {
        lightningrod *obj = new lightningrod();
        obj->solve(in, out);
    }
};

int32_t main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    Solver solver;
    std::istream& in(std::cin);
    std::ostream& out(std::cout);
    solver.solve(in, out);
    return 0;
}

Compilation message (stderr)

lightningrod.cpp: In member function 'void lightningrod::solve(std::istream&, std::ostream&)':
lightningrod.cpp:31:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d", &n);
         ~~~~~^~~~~~~~~~
lightningrod.cpp:34:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%d %d", &a, &b);
             ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 4
• Subtask 2: 7 / 7
• Subtask 3: 12 / 12
• Subtask 4: 21 / 21
• Subtask 5: 26 / 26
• Subtask 6: 0 / 10
• Subtask 7: 0 / 20