poj2007——Scrambled Polygon

对各个点进行极角排序，然后输出，搞定！

#include<stdio.h>#include<math.h>#include<string.h>#define max 55struct node {int x,y;}min,g[max],stack[max];int top,n;int pan(node yuan,node zhong,node last){return (yuan.x-zhong.x)*(last.y-zhong.y)-(last.x-zhong.x)*(yuan.y-zhong.y); }int dis(node a,node b){return (a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y);}void sort(){int i,j,k=0;min=g[0];for(i=1;i<n;i++){if(g[i].y<min.y||(g[i].y==min.y&&g[i].x<min.x)){min=g[i];k=i;}}min=g[k];g[k]=g[0];g[0]=min;for(i=1;i<n-1;i++){k=i;for(j=i+1;j<n;j++){if(pan(g[0],g[k],g[j])>0||(pan(g[0],g[k],g[j])==0&&dis(g[0],g[k])>dis(g[0],g[j])))k=j;}min=g[i];g[i]=g[k];g[k]=min;}for(i=0;i<n;i++){if(g[i].x==0&&g[i].y==0)k=i;}for(i=k;i<n;i++)printf("(%d,%d)/n",g[i].x,g[i].y);for(i=0;i<k;i++)printf("(%d,%d)/n",g[i].x,g[i].y);}int main(){int i=0,j;int a,b;while(scanf("%d%d",&a,&b)!=EOF){g[i].x=a;g[i].y=b;i++;}n=i;sort();return 0;}