几何计算模板

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <vector>
#include <iostream>
#include <cassert>

using namespace std;

typedef long long lld;

const double EPS = 1e-9;
const int MOD = 998244353;

int sign(double x) {return x < -EPS ? -1 : x > EPS;}

struct Point {
    lld x, y;
    Point() {}
    Point(const lld &x, const lld &y): x(x), y(y) {}

    void in() {
        cin >> x >> y;
    }

    bool dim() const {
        return x < 0 || x == 0 && y < 0;
    }
};

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);
}
lld operator * (const Point &a, const Point &b) {
    return a.x * b.y - a.y * b.x;
}
bool operator < (const Point &a, const Point &b) {
    if (a.dim() == b.dim()) {
        return a * b > 0;
    }else {
        return a.dim() > b.dim();
    }
}

typedef vector<Point> Points;

lld pow_mod(lld x, lld n) {
    lld ret = 1;
    while (n) {
        if (n & 1) ret = ret * x % MOD;
        n >>= 1; x = x * x % MOD;
    }
    return ret;
}

inline void add(int &x, int ad) {
    x += ad;
    if (x >= MOD) x -= MOD;
}

lld area(const Point &a, const Point &b) {
    return a * b;
}

int n, tot;
lld pw2[1005];
Point vec[1005];

void work() {
    scanf("%d", &n);
    Points points(n);
    for (int i = 0; i < n; i++) {
        points[i].in();
    }
    int ans = 0;
    for (int i = 0; i < n; i++) {
        tot = 0;
        for (int j = 0; j < n; j++) {
            if (j == i) continue;
            vec[tot ++] = points[j] - points[i];
        }
        sort(vec, vec + tot);
        for (int j = 0; j < tot; j++) {
            int l = 1, r = tot - 1;    
            while (r >= l) {
                int mid = (r + l) >> 1;
                int Mid = (mid + j) % tot;
                if (vec[j] * vec[Mid] > 0) {
                    l = mid + 1;
                }else {
                    r = mid - 1;
                }
            }
            -- l;
            add(ans, (area(points[i], points[i] + vec[j]) % MOD * (pw2[l] - 1) % MOD + MOD) % MOD);
        }
    }
    printf("%d
", ans);
}

int main() {
    pw2[0] = 1;
    for (int i = 1; i <= 1000; i++) {
        pw2[i] = 2 * pw2[i-1] % MOD;
    }
    int T;
    scanf("%d", &T);
    for (int cas = 1; cas <= T; cas++) {
        work();
    }
    return 0;
}

 doublle型

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
#include <cmath>
#include <cassert>
#include <set>

using namespace std;

const double Pi = 3.14159265358979324;
const double EPS = 1e-8;

int sign(double x) {return x < -EPS ? -1 : x > EPS;}

struct Point {
    double x, y;
    
    Point() {}
    Point(const double &x, const double &y): x(x), y(y) {}

    double norm() const {
        return sqrt(x * x + y * y);
    }

    double ang() const {
        return atan2(y, x);
    }
    
    Point util() const {
        return Point(x / norm(), y / norm());
    }

    void in() {
        scanf("%lf%lf", &x, &y);
    }
};

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);
}
Point operator * (const double &b, const Point &a) {
    return Point(a.x * b, a.y * b);
}
double operator * (const Point &a, const Point &b) {
    return a.x * b.y - a.y * b.x;
}
bool operator < (const Point &a, const Point &b) {
    return sign(a.x - b.x) < 0 ||
        sign(a.x - b.x) == 0 && sign(a.y - b.y) < 0;
}
bool operator != (const Point &a, const Point &b) {
    return sign(a.x - b.x) || sign(a.y - b.y);
}
bool operator == (const Point &a, const Point &b) {
    return sign(a.x - b.x) == 0 && sign(a.y - b.y) == 0;
}

typedef vector<Point> Points;
typedef vector<Point> Convex;

Point rotate(const Point &a, const double &ang) {
    double x = a.x * cos(ang) - a.y * sin(ang);
    double y = a.x * sin(ang) + a.y * cos(ang);
    return Point(x, y);
}

int convex_hull(Points &ps, Convex &reg) {
    int n = ps.size();
    if (n <= 2) {
        reg = ps; return n;
    }
    sort(ps.begin(), ps.end());
    reg.resize(n * 2);
    int k = 0;
    for (int i = 0; i < n; i++) {
        while (k > 1 && sign((reg[k-1] - reg[k-2]) * (ps[i] - reg[k-1])) <= 0) -- k;
        reg[k ++] = ps[i];
    }
    for (int i = n - 2, t = k; i >= 0; i--) {
        while (k > t && sign((reg[k-1] - reg[k-2]) * (ps[i] - reg[k-1])) <= 0) -- k;
        reg[k ++] = ps[i];
    }
    reg.resize(k - 1);
    return reg.size();
}

struct Line {
    Point s, d;
    Line() {}
    Line(const Point &a, const Point &b): s(a), d(b - a) {}
};

Point line_line_cross(const Line &a, const Line &b) {
    assert(sign(a.d * b.d) != 0);
    double lambda(((b.s - a.s) * b.d) / (a.d * b.d));
    return a.s + lambda * a.d;
}

struct Circle {
    Point c;
    double r;
    Circle() {}
    Circle(const Point &a, const double &b): c(a), r(b) {}

    Point point(const double &ang) const {
        return Point(c.x + cos(ang) * r, c.y + sin(ang) * r);
    }

    double area() const {
        return r * r * Pi;
    }
    double peri() const {
        return 2 * r * Pi;
    }
    
    void in() {
        c.in(); scanf("%lf", &r);
    }
};

int circle_circle_cross(const Circle &a, const Circle &b, Points &reg) {
    double d = (a.c - b.c).norm();
    if (sign(d) == 0) {
        if (sign(a.r - b.r) == 0) return -1;
        return 0;
    }
    if (sign(a.r + b.r - d) < 0) return 0 ;
    if (sign(fabs(a.r - b.r) - d) > 0) return 0;

    double ang = (b.c - a.c).ang();
    double da = acos((a.r * a.r + d * d - b.r * b.r) / (2 * a.r * d));
    Point p1 = a.point(ang - da), p2 = a.point(ang + da);

    reg.push_back(p1);
    if (p1 == p2) return 1;
    reg.push_back(p2);
    return 2;
}


int main() {
    return 0;
}

 极角排序

#include<bits/stdc++.h>
using namespace std;
const int M = 2e3 + 10 ;
typedef long long ll ;

int n ;
struct Point {
       int  x , y ;
       Point () {} 
       Point (const int &x , const int &y) :
               x(x) , y(y) {}
       int dim() const {
               return x < 0 || x == 0 && y < 0 ;
       }
       void in () { cin >> x >> y ; }
} a[M] ;
Point b[M] ;
ll tot , cut ;
int operator * (const Point &a , const Point &b) {
        return a.x*b.y - a.y*b.x ;
}

bool operator < (const Point &a, const Point &b) {
    if (a.dim() == b.dim()) {
        return a * b > 0;
    }else {
        return a.dim() > b.dim();
    }
}

bool operator == (const Point &a , const Point &b) {
        return !(a < b) && !(b < a);
}

int main () {
        ios::sync_with_stdio (false) ;
        cin >> n ;
        for (int i = 0 ; i < n ; i ++) a[i].in () ;
        tot = 1ll*n*(n-1)*(n-2) / 6 ;

        for (int i = 0 ; i < n ; i ++) {
                for (int j = 0 , N = 0 ; j < n ; j ++) {
                        if (i == j) continue ;
                        b[N] = Point (a[j].x-a[i].x , a[j].y-a[i].y) ;
                        N ++ ;
                }
                sort (b , b + n-1 ) ;
                int tmp = 0 ;
                for (int j = 1 ; j < n-1 ; j ++) {
                        if (b[j] == b[j-1]) tmp ++ ;
                        else {
                                cut += 1ll * (tmp+1) * tmp / 2 ;
                                tmp = 0 ;
                        }
                }
                cut += 1ll * (tmp+1) * tmp / 2 ;
        }
        cout << tot - cut/2 << endl ;
        return 0 ;
}

恩，碰到有重点的情况，你在结构体里要放上id这个属性，在x,y都相等的时候，再按照id拍个序，不然会出现各种re , tle。

今天２０１６．７．２０打多校，我的同伴们就因为这个原因，卡了很长时间。

额，讲道理，还是要感谢他们检查除了这个bug ＠仓鼠＠幻神。