苛刻的算法,只告诉你是否大于,让你求出具体值

zerozero_nine

有点趣味, 用Dev-C写写看.
#include <iostream.h>;
#include <time.h>;

double generate_unknown()
{
double result;
    srand(time(0));
    result = rand()/100.0; // range : 0.00 to 327.67
    if (rand()%2) result = -result;
    return result; // range : -327.67 to 327.67
}

double find_upper(double unknown)
{
double result=1;
    while (unknown>;result) result*=2;
    return result;   
}

double find_lower(double unknown, double result)
{
    while (!(unknown>;result)) result/=2;
    return result;
}

double run(double unknown)
{
double mid, upper, lower;
    upper = find_upper(unknown);
    cout<<"upper = "<<upper<<endl;
    lower = find_lower(unknown,upper);
    cout<<"lower = "<<lower<<endl;
    while (upper-lower>;0.0001) {
        mid=(upper+lower)/2;
        if (unknown>;mid) lower=mid;
        else upper=mid;
        cout<<mid<<endl;
    }
    return mid;
}

int main()
{
double unknown;
    unknown = generate_unknown();
    cout<<"Unknown value is : "<<unknown<<endl;
    if (unknown>;0) cout<<unknown<<' '<<run(unknown)<<endl;
    else cout<<unknown<<' '<<-run(-unknown)<<endl;
    system("AUSE";
    exit(0);
}