TopCoder SRM 152 DIV2 250pt

FixedPointTheorem.cpp

#define FOR(i,a,b) for(int i=(a);i<(b);++i)

class FixedPointTheorem {
public:
    double cycleRange(double R) {
        double x = 0.25;
        FOR(i, 0, 200000){
            x = R * x * (1 - x);
        }
        double min = x, max = x;
        FOR(i, 200000, 201001){
            if(max < x) max = x;
            if(min > x) min = x;
            x = R * x * (1 - x);
        }
        double result = max - min;
        return result;
    }

};