//冒号排序
-(void)sort:(NSMutableArray *)array{
int i, y;
for (i =0; i < [arraycount]; i++) {
//每次参加比较的最后一个元素一定是最大的
for (y =0; y < [arraycount] - i -1; y++) {
if ([[arrayobjectAtIndex:y]intValue] > [[arrayobjectAtIndex:y+1]intValue]) {
[array exchangeObjectAtIndex:ywithObjectAtIndex:y +1];
}
}
}
}
//素数的判断（6n+1、6n-1）
- (BOOL)isPrime:(int)x {
if (x <= 3) {
return x > 1;
} elseif (x %2 == 0 || x %3 == 0) {
return NO;
} else {
for (int i = 5; i * i <= x; i +=6) {
if (x % i == 0 || x % (i+2) == 0) {
return NO;
}
}
return YES;
}
}