这应该适用于 2 分母的任何幂:
// dodge this special case:
[fractionArray addObject:@"0"];
for ( int numerator = 1; numerator <= 15; numerator++ )
{
int denominator = 16;
int num = numerator;
while ( num % 2 == 0 )
{
num /= 2;
denominator /= 2;
}
NSString *fracString = [NSString stringWithFormat:@"%d/%d", num, denominator];
[fractionArray addObject:fracString]; // Add the string.
}
并且很容易将其扩展到任何分母。(提示:用 n 替换 2,从 2 到 sqrt(分母)迭代 n。)
编辑:现在真的有效!
由于我继续对其进行编码,因此这是考虑任何分母的版本:
int denominator = 240;
for ( int numerator = 1; numerator < denominator; numerator++ )
{
int denom = denominator;
int num = numerator;
int factor = 2;
while ( factor * factor < denom )
{
while ( (num % factor) == 0 && (denom % factor) == 0 )
{
num /= factor;
denom /= factor;
}
// don't worry about finding the next prime,
// the loop above will skip composites
++factor;
}
NSString *fracString = [NSString stringWithFormat:@"%d/%d", num, denom];
[fractionArray addObject:fracString];
}