Language: C++

#include<iostream>
#include<string>
#include<cstdio>
#include<cstring>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<deque>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<complex>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<utility>
#include<cassert>
using namespace std;

const ll mod=1e9+7 ;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
#define fr first
#define sc second
#define all(c) c.begin(),c.end()
#define pb push_back
#define debug(x)  cout << #x << " = " << (x) << endl;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
//#define int long long

////////////////////////////
// 基本要素 (点, 線分, 円)
////////////////////////////

using DD = double;
const DD INF = 1LL<<60;      // to be set appropriately
const DD EPS = 1e-10;        // to be set appropriately
const DD PI = acos(-1.0);
DD torad(int deg) {return (DD)(deg) * PI / 180;}
DD todeg(DD ang) {return ang * 180 / PI;}

/* Point */
struct Point {
    DD x, y;
    Point(DD x = 0.0, DD y = 0.0) : x(x), y(y) {}
    friend ostream& operator << (ostream &s, const Point &p) {return s << '(' << p.x << ", " << p.y << ')';}
};
inline Point operator + (const Point &p, const Point &q) {return Point(p.x + q.x, p.y + q.y);}
inline Point operator - (const Point &p, const Point &q) {return Point(p.x - q.x, p.y - q.y);}
inline Point operator * (const Point &p, DD a) {return Point(p.x * a, p.y * a);}
inline Point operator * (DD a, const Point &p) {return Point(a * p.x, a * p.y);}
inline Point operator * (const Point &p, const Point &q) {return Point(p.x * q.x - p.y * q.y, p.x * q.y + p.y * q.x);}
inline Point operator / (const Point &p, DD a) {return Point(p.x / a, p.y / a);}
inline Point conj(const Point &p) {return Point(p.x, -p.y);}
inline Point rot(const Point &p, DD ang) {return Point(cos(ang) * p.x - sin(ang) * p.y, sin(ang) * p.x + cos(ang) * p.y);}
inline Point rot90(const Point &p) {return Point(-p.y, p.x);}
inline DD cross(const Point &p, const Point &q) {return p.x * q.y - p.y * q.x;}
inline DD dot(const Point &p, const Point &q) {return p.x * q.x + p.y * q.y;}
inline DD norm(const Point &p) {return dot(p, p);}
inline DD abs(const Point &p) {return sqrt(dot(p, p));}
inline DD amp(const Point &p) {DD res = atan2(p.y, p.x); if (res < 0) res += PI*2; return res;}
inline bool eq(const Point &p, const Point &q) {return abs(p - q) < EPS;}
inline bool operator < (const Point &p, const Point &q) {return (abs(p.x - q.x) > EPS ? p.x < q.x : p.y < q.y);}
inline bool operator > (const Point &p, const Point &q) {return (abs(p.x - q.x) > EPS ? p.x > q.x : p.y > q.y);}
inline Point operator / (const Point &p, const Point &q) {return p * conj(q) / norm(q);}

/* Line */
struct Line : vector<Point> {
    Line(Point a = Point(0.0, 0.0), Point b = Point(0.0, 0.0)) {
        this->push_back(a);
        this->push_back(b);
    }
    friend ostream& operator << (ostream &s, const Line &l) {return s << '{' << l[0] << ", " << l[1] << '}';}
};

/* Circle */
struct Circle : Point {
    DD r;
    Circle(Point p = Point(0.0, 0.0), DD r = 0.0) : Point(p), r(r) {}
    friend ostream& operator << (ostream &s, const Circle &c) {return s << '(' << c.x << ", " << c.y << ", " << c.r << ')';}
};


///////////////////////
// 多角形アルゴリズム
///////////////////////

// 凸包
vector<pair<Point, int> > ConvexHull(vector<pair<Point, int>> &ps) {
    int n = (int)ps.size();
    vector<pair<Point, int> > res(2*n);
    sort(ps.begin(), ps.end());
    int k = 0;
    for (int i = 0; i < n; ++i) {
        if (k >= 2) {
            while (cross(res[k-1].first - res[k-2].first, ps[i].first - res[k-2].first) < EPS) {
                --k;
                if (k < 2) break;
            }
        }
        res[k].first = ps[i].first;
        res[k].second = ps[i].second;
        ++k;
    }
    int t = k+1;
    for (int i = n-2; i >= 0; --i) {
        if (k >= t) {
            while (cross(res[k-1].first - res[k-2].first, ps[i].first - res[k-2].first) < EPS) {
                --k;
                if (k < t) break;
            }
        }
        res[k].first = ps[i].first;
        res[k].second = ps[i].second;
        ++k;
    }
    res.resize(k-1);
    return res;
}

void solve() {
	int n; cin >> n;
    vector<pair<POint, int>> vp(n);
    rep(i, n) cin >> vp[i].fr.x >> vp[i].fr.y, vp[i].sc = i;

    auto ch = ConvexHull(vp);
    int m = ch.size();

    vector<DD> res(n, 0.0);
    rep(i, m) {
        int id = ch[i].sc;
        //Pointはベクトルみたいなもの
        Ponit prev = rot90(ch[(i-1+m)%m].fr - ch[i].fr);
        Point next = rot90(ch[i].fr - ch[(i+1)%m]);
        DD prevang = amp(prev);
        DD nextang = amp(next);
        DD ang = nextang - prevang;
        if(ang < 0) ang += PI * 2;

        DD prob = ang / (PI * 2);
        res[id] = prob;
    }

    rep(i, n) {
        cout << res[i] << endl;
    }
}

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout << fixed << setprecision(10);
	//init();
	solve();
	//cout << "finish" << endl;
    return 0;
}

Compiler output:
a.cc:24:7: error: 'll' does not name a type; did you mean 'all'?
   24 | const ll mod=1e9+7 ;
      |       ^~
      |       all
a.cc: In function 'void solve()':
a.cc:132:17: error: 'POint' was not declared in this scope; did you mean 'Point'?
  132 |     vector<pair<POint, int>> vp(n);
      |                 ^~~~~
      |                 Point
a.cc:132:24: error: template argument 1 is invalid
  132 |     vector<pair<POint, int>> vp(n);
      |                        ^~~
a.cc:132:27: error: template argument 1 is invalid
  132 |     vector<pair<POint, int>> vp(n);
      |                           ^~
a.cc:132:27: error: template argument 2 is invalid
a.cc:133:24: error: invalid types 'int[int]' for array subscript
  133 |     rep(i, n) cin >> vp[i].fr.x >> vp[i].fr.y, vp[i].sc = i;
      |                        ^
a.cc:133:38: error: invalid types 'int[int]' for array subscript
  133 |     rep(i, n) cin >> vp[i].fr.x >> vp[i].fr.y, vp[i].sc = i;
      |                                      ^
a.cc:133:50: error: invalid types 'int[int]' for array subscript
  133 |     rep(i, n) cin >> vp[i].fr.x >> vp[i].fr.y, vp[i].sc = i;
      |                                                  ^
a.cc:135:26: error: invalid initialization of reference of type 'std::vector<std::pair<Point, int> >&' from expression of type 'int'
  135 |     auto ch = ConvexHull(vp);
      |                          ^~
a.cc:98:64: note: in passing argument 1 of 'std::vector<std::pair<Point, int> > ConvexHull(std::vector<std::pair<Point, int> >&)'
   98 | vector<pair<Point, int> > ConvexHull(vector<pair<Point, int>> &ps) {
      |                                      ~~~~~~~~~~~~~~~~~~~~~~~~~~^~
a.cc:142:9: error: 'Ponit' was not declared in this scope; did you mean 'Point'?
  142 |         Ponit prev = rot90(ch[(i-1+m)%m].fr - ch[i].fr);
      |         ^~~~~
      |         Point
a.cc:144:25: error: invalid initialization of reference of type 'const Point&' from expression of type '<unresolved overloaded function type>'
  144 |         DD prevang = amp(prev);
      |                      ~~~^~~~~~
a.cc:70:28: note: in passing argument 1 of 'DD amp(const Point&)'
   70 | inline DD amp(const Point &p) {DD res = atan2(p.y, p.x); if (res < 0) res += PI*2; return res;}
      |               ~~~~~~~~~~~~~^