HDU 1006.Tick and Tick【11月12】【很久没写博客了】

Tick and Tick

Problem Description

The three hands of the clock are rotating every second and meeting each other many times everyday. Finally, they get bored of this and each of them would like to stay away from the other two. A hand is happy if it is at least D degrees from any of the rest. You are to calculate how much time in a day that all the hands are happy.

 

Input

The input contains many test cases. Each of them has a single line with a real number D between 0 and 120, inclusively. The input is terminated with a D of -1.

 

Output

For each D, print in a single line the percentage of time in a day that all of the hands are happy, accurate up to 3 decimal places.

 

Sample Input

012090-1

 

Sample Output

100.0000.0006.251

题意很简单，时钟三个指针之间的夹角大于D的时间在一天中所占的比例。具体思路看代码很清晰：

#include <iostream>#include <cstdio>#include <cstring>#include <string>#include <map>#include <algorithm>using namespace std;double MAX(double a, double b, double c){    if(a >= b && a >= c) return a;    else if(b >= c) return b;    else return c;}double MIN(double a, double b, double c){    if(a <= b && a <= c) return a;    else if(b <= c) return b;    else return c;}int main(){    double s = 360. / 60., m = 360. / 3600., h = 360. / 43200.;//角速度    double m_s = s - m, h_m = m - h, h_s = s - h;//相对较速度    //cout << m_s <<" "<< h_m <<" "<< h_s << endl;    double D,x_m_s,x_h_s,x_h_m,y_m_s,y_h_s,y_h_m;//周期    double cycle_m_s = 360 / m_s;    double cycle_h_m = 360 / h_m;    double cycle_h_s = 360 / h_s;    //cout << cycle_m_s <<" "<< cycle_h_m <<" "<< cycle_h_s << endl;    while(scanf("%lf",&D) == 1 && D != -1)    {        //cout << D << endl;        x_m_s = D / m_s;//周期内合法区间        x_h_m = D / h_m;        x_h_s = D / h_s;        y_m_s = (360 - D) / m_s;        y_h_m = (360 - D) / h_m;        y_h_s = (360 - D) / h_s;        //cout << x_m_s <<" "<< y_m_s << endl;        //cout << x_h_m <<" "<< y_h_m << endl;        //cout << x_h_s <<" "<< y_h_s << endl;        double sumtime = 0;        double begintime, endtime;        //寻找交集        for(double begin1 = x_m_s,end1 = y_m_s; end1 < 43200.000001; begin1 += cycle_m_s,end1 += cycle_m_s)        {            for(double begin2 = x_h_m,end2 = y_h_m; end2 < 43200.000001; begin2 += cycle_h_m,end2 += cycle_h_m)            {                if(end1 < begin2) break;                if(end2 < begin1) continue;                for(double begin3 = x_h_s,end3 = y_h_s; end3 < 43200.000001; begin3 += cycle_h_s,end3 += cycle_h_s)                {                    if(begin3 > end1 || begin3 > end2) break;                    if(begin1 > end3 || begin2 > end3) continue;                    begintime = MAX(begin1, begin2, begin3);                    endtime = MIN(end1, end2, end3);                    if(endtime > begintime) sumtime += (endtime - begintime);                }            }        }        printf("%.3f\n", sumtime / 432);    }    return 0;}

啊····好久没写博客了····