hdu 1077计算几何

比较简单的计算几何，首先枚举两个在圆上的点，然后数一数多少个点在此圆上，复杂度n^3。但是要注意的是如果这样得到的结果是0，那么还是要输出1，因为至少可以捞一条鱼，这是一个易错点！

/*

 * hdu1077/win.cpp

 * Created on: 2012-10-25

 * Author    : ben

 */

#include <cstdio>

#include <cstdlib>

#include <cstring>

#include <cmath>

#include <ctime>

#include <iostream>

#include <algorithm>

#include <queue>

#include <set>

#include <map>

#include <stack>

#include <string>

#include <vector>

#include <deque>

#include <list>

#include <functional>

#include <numeric>

#include <cctype>

using namespace std;

const int MAXN = 310;

const double eps = 1e-4;

typedef struct MyPoint {

    double x, y;

    MyPoint() {        x = y = 0;    }

    MyPoint(double xx, double yy) {        x = xx;        y = yy;    }

    MyPoint(const MyPoint &p1, const MyPoint &p2) {

        x = (p1.x + p2.x) / 2;

        y = (p1.y + p2.y) / 2;

    }

}MyPoint;

inline double mydistance(const MyPoint &p1, const MyPoint &p2) {

    return sqrt((p1.x - p2.x) * (p1.x - p2.x) + (p1.y - p2.y) * (p1.y - p2.y));

}

inline MyPoint operator-(const MyPoint &p1, const MyPoint &p2) {

    return MyPoint(p1.x - p2.x, p1.y - p2.y);

}

MyPoint points[MAXN];

int N, ans;



inline void getcenter(const MyPoint &p1, const MyPoint &p2, MyPoint &c) {

    MyPoint diff = p1 - p2;

    MyPoint mid(p1, p2);

    double angle;

    double high = mydistance(p1, p2) / 2;

    high = sqrt(1 - high * high);

    if (fabs(diff.x) < eps) {

        c.x = mid.x + high;

        c.y = mid.y;

    } else {

        angle = atan(diff.y / diff.x);

        c.x = mid.x - high * sin(angle);

        c.y = mid.y + high * cos(angle);

    }

}



inline bool myjudge(const MyPoint &p1, const MyPoint &p2) {

    double dis = mydistance(p1, p2);

    return dis <= 1 + eps;

}



int main() {

#ifndef ONLINE_JUDGE

    freopen("data.in" , "r", stdin);

#endif

    int T;

    scanf("%d", &T);

    while(T--) {

        scanf("%d", &N);

        for(int i = 0; i < N; i++) {

            scanf("%lf%lf", &points[i].x, &points[i].y);

        }

        ans = 1;

        MyPoint p;

        for(int i = 0; i < N; i++) {

            for(int j = i + 1; j < N; j++) {

                if(mydistance(points[i], points[j]) > 2 + eps + eps) {

                    continue;

                }

                getcenter(points[i], points[j], p);

                int t = 0;

                for(int k = 0; k < N; k++) {

                    if(myjudge(p, points[k])) {

                        t++;

                    }

                }

                if(t > ans) {

                    ans = t;

                }

            }

        }

        printf("%d\n", ans);

    }

    return 0;

}