tjut 4643

来源：互联网发布：高中教学视频淘宝网编辑：程序博客网时间：2024/06/10 18:36
#include <cstdio>#include <cmath>const double eps = 1e-8;inline int dcmp(double x) {    if(fabs(x) < eps) return 0;    return x > eps ? 1 : -1;}struct point {    double x, y;    point(double x, double y) :            x(x), y(y) {    }    point() {    }    point operator+(const point &t) const {        return point(x + t.x, y + t.y);    }    point operator-(const point &t) const {        return point(x - t.x, y - t.y);    }    point operator*(const double &t) const {            return point(x*t, y*t);    }    inline void in() {        scanf("%lf%lf", &x, &y);    }} sta[55], city[55], tt, tp;struct line {    point a, b;    line(point a, point b) :            a(a), b(b) {    }    line() {    }} l[50][50];int n, m, k;inline line getMidLine(const point &a, const point &b) {    point mid = (a + b) *0.5;    point tp = b-a;    return line(mid, mid+point(-tp.y, tp.x));}inline double cross(const point &a, const point &b) {    return a.x*b.y-a.y*b.x;}inline point intersect(const point &a, const point &b, const point &l, const point &r) {    point ret = a;    double t = ((a.x - l.x) * (l.y - r.y) - (a.y - l.y) * (l.x - r.x))            / ((a.x - b.x) * (l.y - r.y) - (a.y - b.y) * (l.x - r.x));    ret.x += (b.x - a.x) * t;    ret.y += (b.y - a.y) * t;    return ret;}inline bool dotOnSeg(const point &p, const point &l, const point &r) {  //判点在线段上    return (p.x-l.x)*(p.x-r.x) < eps    && (p.y-l.y)*(p.y-r.y) < eps;}inline double dis(const point &a, const point &b) {    return sqrt( (a.x-b.x)*(a.x-b.x) + (a.y-b.y)*(a.y-b.y));}inline bool judge(const point &p, int &a) {    double d = dis(p, sta[a]);    int i;    for(i = 0; i < m; i++) if(i != a)        if(d > dis(p, sta[i])+eps) return 0;    return 1;}int a, b, ans;int main() {    int i, j;    while (~scanf("%d%d", &n, &m)) {        for (i = 0; i < n; i++) city[i].in();        for (i = 0; i < m; i++) sta[i].in();        for (i = 0; i < m; i++)            for (j = i + 1; j < m; j++)                l[i][j] = getMidLine(sta[i], sta[j]);        scanf("%d", &k);        while(k--) {            ans = 0;            scanf("%d%d", &a, &b);            a--; b--;            tt = city[a]-city[b];            for(i = 0; i < m; i++)                for(j = i+1; j < m; j++) {                    if(!dcmp(cross(tt, l[i][j].a-l[i][j].b))) continue;                    tp = intersect(city[a], city[b], l[i][j].a, l[i][j].b);                    if(dotOnSeg(tp, city[a], city[b]))                        ans += judge(tp, i);                }            printf("%d\n", ans);        }    }    return 0;}
0 0