UVA579-时钟的指示

#include <iostream>
#include <iomanip>
using namespace std;
int main ()
{
    int h, m;
    double a1, a2,angle;
    char c;
    while(cin>>h>>c>>m)
    {
        if(!h&&!m)break;
        if(h==12)h = 0;
        a1 = (h+m/60.0)*30.0;
        a2 = m*6.0;
        angle = a2 - a1;                                  //cout<<a1<<" "<<a2<<endl;cout<<angle<<"->";
                                                          //if(angle<-180)angle+=360;
        if(angle<0)angle *= -1;
        angle = angle < 360 - angle ? angle : 360 - angle;
                                                         //if(angle<0)angle += 360;
                                                         //while(angle>180)
                                                         //   angle -=180;
        cout<<fixed<<setprecision(3)<<angle<<endl;
    }
    return 0;
}


此题思路错误
我拿angle与180相加减，如碰见181这样的值就不行了。所以这次我败在了思路上。啊啊啊啊啊啊！@