제출 #985302

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
985302		crimson231	Lonely mdic (kriii1_L)	C++17	컴파일 에러	0 ms	0 KiB

L

#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>
#include <set>

using namespace std;

typedef long long ll;
typedef double ld;

const ld PI = acos(-1);
const ld TOL = 1e-9;

struct Circle {
    int x, y, r;
    Circle(int X = 0, int Y = 0, int R = 0) : x(X), y(Y), r(R) {}
};

struct Event {
    ld angle;
    int type; // -1 for entering, 1 for exiting
    int index;

    Event(ld a, int t, int i) : angle(a), type(t), index(i) {}

    bool operator<(const Event& e) const {
        if (abs(angle - e.angle) > TOL)
            return angle < e.angle;
        return type > e.type; // start events (-1) come before end events (1)
    }
};

bool circlesIntersect(const Circle& a, const Circle& b) {
    ll dx = a.x - b.x;
    ll dy = a.y - b.y;
    ll distSq = dx * dx + dy * dy;
    ll radSumSq = (ll)(a.r + b.r) * (a.r + b.r);
    return distSq < radSumSq;
}

ld calculateUnionArea(const vector<Circle>& circles, int excludeIndex = -1) {
    int n = circles.size();
    vector<Event> events;

    for (int i = 0; i < n; ++i) {
        if (i == excludeIndex) continue;
        Circle c = circles[i];
        events.emplace_back(c.x - c.r, -1, i);
        events.emplace_back(c.x + c.r, 1, i);
    }

    sort(events.begin(), events.end());

    set<pair<int, int>> activeCircles;
    ld unionArea = 0.0;
    ld lastX = 0.0;

    for (const auto& event : events) {
        ld currentX = event.angle;

        if (!activeCircles.empty()) {
            ld width = currentX - lastX;
            set<pair<int, int>> currentActiveCircles = activeCircles;

            vector<pair<int, int>> segments;
            for (const auto& circle : currentActiveCircles) {
                int i = circle.second;
                ld y1 = circles[i].y - sqrt((ld)circles[i].r * circles[i].r - (ld)(currentX - circles[i].x) * (currentX - circles[i].x));
                ld y2 = circles[i].y + sqrt((ld)circles[i].r * circles[i].r - (ld)(currentX - circles[i].x) * (currentX - circles[i].x));
                segments.emplace_back(y1, y2);
            }

            sort(segments.begin(), segments.end());

            ld currentHeight = 0.0;
            ld start = -INF;
            for (const auto& seg : segments) {
                if (seg.first > start) {
                    unionArea += currentHeight * width;
                    start = seg.first;
                    currentHeight = seg.second - seg.first;
                } else {
                    if (seg.second > start) {
                        currentHeight += seg.second - start;
                        start = seg.second;
                    }
                }
            }
            unionArea += currentHeight * width;
        }

        if (event.type == -1) {
            activeCircles.insert({circles[event.index].y, event.index});
        } else {
            activeCircles.erase({circles[event.index].y, event.index});
        }

        lastX = currentX;
    }

    return unionArea;
}

void solve() {
    int N;
    cin >> N;
    vector<Circle> circles(N);
    for (int i = 0; i < N; ++i) {
        cin >> circles[i].x >> circles[i].y >> circles[i].r;
    }

    ld totalUnionArea = calculateUnionArea(circles);
    int count = 0;

    for (int i = 0; i < N; ++i) {
        ld unionAreaWithoutCircle = calculateUnionArea(circles, i);
        if (abs(totalUnionArea - unionAreaWithoutCircle) < TOL) {
            count++;
        }
    }

    cout << count << "\n";
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    solve();
    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

L.cpp: In function 'ld calculateUnionArea(const std::vector<Circle>&, int)':
L.cpp:77:25: error: 'INF' was not declared in this scope
   77 |             ld start = -INF;
      |                         ^~~