极角排序合集

来源：互联网发布：传真服务器软件编辑：程序博客网时间：2024/06/07 07:33

poj 2007

#include <iostream>#include <cstdio>#include <cstdlib>#include <cmath>#include <algorithm>using namespace std;struct point{    int x,y;    bool operator<(point k)const{        int t=k.y*x-k.x*y;        return t>0?true:false;    }}p[100];int main(){    int n=0;    while(scanf("%d%d",&p[n].x,&p[n].y)!=EOF)n++;    sort(p+1,p+n);    for(int i=0;i<n;i++){        printf("(%d,%d)\n",p[i].x,p[i].y);    }    return 0;}

lightoj 1285

#include <iostream>#include <cstdio>#include <cstdlib>#include <cmath>#include <algorithm>using namespace std;const int maxn=2000+5;struct point{    int x,y,id;    bool operator<(point b)const{        return x==b.x?y<b.y:x<b.x;    }}p[maxn];int len(int x,int y){    return x*x+y*y;}bool cmp(point z,point k){    int t=(k.y-p[0].y)*(z.x-p[0].x)-(k.x-p[0].x)*(z.y-p[0].y);    if(t==0)return len(z.x-p[0].x,z.y-p[0].y)<len(k.x-p[0].x,k.y-p[0].y);    return t>0;}int main(){    int t;    scanf("%d",&t);    for(int cas=1;cas<=t;cas++){        int n;        scanf("%d",&n);        for(int i=0;i<n;i++){            scanf("%d%d",&p[i].x,&p[i].y);            p[i].id=i;        }        sort(p,p+n);        sort(p+1,p+n,cmp);        printf("Case %d:\n",cas);        point tt=p[n-1];        int pos=n-1;        for(int i=n-2;i>=0;i--){            int tmp=(tt.y-p[0].y)*(p[i].x-p[0].x)-(tt.x-p[0].x)*(p[i].y-p[0].y);            if(tmp!=0){                break;            }            pos=i;        }        if(pos==0){            printf("Impossible\n");continue;        }        reverse(p+pos,p+n);        for(int i=0;i<n;i++){            printf("%d",p[i].id);            if(i < n-1)printf(" ");            else printf("\n");        }        //printf("\n");    }    return 0;}

poj 1696 Space Ant

#include <iostream>#include <cstdio>#include <cstdlib>#include <cmath>#include <algorithm>using namespace std;const int maxn=60+5;int res[maxn];int pos;struct point{    int x,y,id;    bool operator<(point b)const{        return y==b.y?x<b.x:y<b.y;    }}p[maxn];int len(int x,int y){    return x*x+y*y;}bool cmp(point z,point k){    int t=(k.y-p[pos].y)*(z.x-p[pos].x)-(k.x-p[pos].x)*(z.y-p[pos].y);    if(t==0)return len(z.x-p[pos].x,z.y-p[pos].y)<len(k.x-p[pos].x,k.y-p[pos].y);    return t>0;}int main(){    int t;    scanf("%d",&t);    for(int cas=1;cas<=t;cas++){        int n;        scanf("%d",&n);        for(int i=0;i<n;i++){            scanf("%d%d%d",&p[i].id,&p[i].x,&p[i].y);        }        sort(p,p+n);        pos=0;int k=0;        for(int i=1;i<n;i++){            sort(p+i,p+n,cmp);            res[pos++]=p[k++].id;        }        res[pos++]=p[k++].id;        printf("%d",k);        for(int i=0;i<pos;i++){            printf(" %d",res[i]);        }        printf("\n");    }    return 0;}

0 0