math.c

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#include <limits.h>
 
#include "math.h"
 
long long gcd(long long a, long long b)
{
        // Everything divides 0
        if (a == 0) {
                return b;
        }
        if (b == 0) {
                return a;
        }
 
        // base case
        if (a == b) {
                return a;
        }
 
        // a is greater
        if (a > b) {
                return gcd(a-b, b);
        }
        return gcd(a, b-a);
}
 
long long lcm(long long a, long long b) {
        return a * b / gcd(a, b);
}
 
bool
is_power_of_two(unsigned long long x)
{
        return x != 0 && (x & (x - 1)) == 0;
}
 
unsigned long long
next_power_of_two(unsigned long long x)
{
        if (x <= 1) {
                return 1;
        }
        const int pos = __builtin_clzll(x - 1);
        return pos > 0 ? 1ULL << (sizeof(unsigned long long) * CHAR_BIT - pos)
                       : 0;
}