67 lines
1.0 KiB
C++
67 lines
1.0 KiB
C++
|
/*
|
||
|
|
* YOUR INFO HERE!
|
||
|
|
*/
|
||
|
|
|
||
|
|
// FINAL VERSION:
|
||
|
|
unsigned long long largest_prime_factor(unsigned long long n){
|
||
|
|
unsigned long long lpf, p, s, t;
|
||
|
|
lpf = 1;
|
||
|
|
p = 2;
|
||
|
|
s = 1;
|
||
|
|
t = n / p;
|
||
|
|
|
||
|
|
while (p <= t){
|
||
|
|
if (n % p == 0){
|
||
|
|
lpf = p;
|
||
|
|
n /= p;
|
||
|
|
while (n % p == 0){
|
||
|
|
n /= p;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
p += s;
|
||
|
|
s = 2;
|
||
|
|
t = n / p;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (n > lpf){
|
||
|
|
lpf = n;
|
||
|
|
}
|
||
|
|
|
||
|
|
return lpf;
|
||
|
|
}
|
||
|
|
|
||
|
|
#ifdef EULER_PROBLEM
|
||
|
|
// BUILDING AREA:
|
||
|
|
struct Euler_In{
|
||
|
|
unsigned long long n;
|
||
|
|
};
|
||
|
|
|
||
|
|
struct Euler_Result{
|
||
|
|
unsigned long long lpf;
|
||
|
|
};
|
||
|
|
|
||
|
|
static const unsigned long long NUMBER = 600851475143;
|
||
|
|
|
||
|
|
Euler_Result euler_main(Euler_In in){
|
||
|
|
Euler_Result result;
|
||
|
|
result.lpf = largest_prime_factor(NUMBER);
|
||
|
|
return result;
|
||
|
|
}
|
||
|
|
|
||
|
|
void euler_print(Euler_Result answer, Euler_In in){
|
||
|
|
printf("%llu\n", answer.lpf);
|
||
|
|
}
|
||
|
|
|
||
|
|
#if 0
|
||
|
|
#define EULER_CHECK
|
||
|
|
|
||
|
|
bool euler_check(Euler_Result answer, Euler_In in){
|
||
|
|
bool result = 1;
|
||
|
|
|
||
|
|
return result;
|
||
|
|
}
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#endif
|
||
|
|
|