极角排序

#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdio>
#include<vector>
#include<cstring>
#include<cstdlib>
#include<stack>
#include<queue>
#include<string>
#include<stdio.h>
#include<map>
#define IOS ios::sync_with_stdio(false)
using namespace std;
const int maxn=1e6+10;
typedef long long ll;
typedef unsigned long long ull;
struct Node{
    double  x,y;
    double val;
    double dis;
    Node(){}
    Node(int x_,int y_){
        x=x_;y=y_;
    }
    Node operator - (const Node &p){
        return Node(x-p.x,y-p.y);
    }
    double operator ^ (const Node &p){
        return x*p.y-y*p.x;
    }
}node[1010];
double cross(double x1,double y1,double x2,double y2){
    return x1*y2-x2*y1;
}
double cmp(Node a,Node b){
    Node c;c.x=0,c.y=0;
    double ans = (a-c)^(b-c);
    return ans>0;
}
int cmp1 (Node a,Node b){
    if(a.val==b.val){
        return a.dis>b.dis;
    }
    return a.val<b.val;

}
double PI = acos(-1.0);
int main(){
    int t;
    int cas=0;
    scanf("%d",&t);
    while(t--){
        int n;scanf("%d",&n);
        for(int i=0;i<n;++i){
            cin>>node[i].x>>node[i].y;
            double v = atan2(node[i].y,node[i].x);
            if(v<0){
                v = v+2*PI;
            }
            node[i].val=v;
            node[i].dis=sqrt(node[i].x*node[i].x+node[i].y*node[i].y);
        }
        sort(node,node+n,cmp1);
        printf("case #%d:\n",cas++);
        for(int i=0;i<n;++i){
            printf("(%.4lf,%.4lf)\n",node[i].dis,node[i].val);
        }
    }

    return 0;
}

B. 极坐标排序 - 编程思维与实践课程模拟练习 - ECNU Online Judge