POJ2653Pick-up sticks

来源：互联网发布：mssql 备份数据库编辑：程序博客网时间：2024/05/22 05:09

枚举每根STICKS后面放的于其是否有焦点.

还有种VECTOR的写法,没搞出来....

#include <iostream>#include <cstdio>#include <cstring>#include <cmath>#include <vector>#include <algorithm>using namespace std;const double INF = 1e-8;int dcmp(double t){    if(fabs(t) < INF) return 0;    if(t < 0)   return -1;    return 1;}struct point{    double x ,y;point (double a = 0,double b = 0){    x = a;y = b;}};typedef point Vector;point operator - (const point &a,const point &b){    return point(a.x - b.x , a.y - b.y);}double cross(point &p,point &l1,point &l2){    return ((l1.x - p.x)*(l2.y - p.y) - (l1.y - p.y)*(l2.x - p.x));}double cross(Vector a,Vector b){    return a.x * b.y - a.y * b.x;}struct segment{    point s,e;    int number;    segment(point a,point b,int n){s = a; e = b;number = n;}    segment(){    s = point(0,0);e = point(0,0);number = 0;}};segment p[1001000];bool SegmentItersection(point a1, point a2, point b1, point b2){    double c1 = cross(a2-a1, b1-a1), c2 = cross(a2-a1, b2-a1),    c3 = cross(b2-b1, a1-b1), c4 = cross(b2-b1, a2-b1);    return dcmp(c1)*dcmp(c2) < 0 && dcmp(c3)*dcmp(c4) < 0;}int pcount = 0;int n;bool flag [1000010];int main(){    int n , topsize;    double x1,x2,y1,y2;    segment temp(point(0,0),point(0,0),0);    int temp1;    while(1){            scanf("%d",&n);                if(n ==0  ) return 0;            memset(flag,0,sizeof(flag));            for(int i = 0 ;i < n; i++)            scanf("%lf%lf%lf%lf",&p[i].s.x,&p[i].s.y,&p[i].e.x,&p[i].e.y);            for(int i = 0 ;i < n ;i++)                    for(int j = i + 1 ; j < n; j++)                        if(SegmentItersection(p[i].e,p[i].s,p[j].e,p[j].s))            {                flag [i] =true;                break;            }            printf("Top sticks: ");        for(int i = 0; i < n; i++)            if(flag[i]==0)            {                if(i==n-1)                    printf("%d.\n",i+1);                else                    printf("%d, ",i+1);            }    }    return 0;}

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