代码

int binary_search(unsigned *a, int n, unsigned X)
{
register unsigned *L = a, *R = a + (100000000 - 1);
register unsigned long long x = X;
	while(L<R){
register unsigned *md = a + (((R - a) * (x - *L) + (L - a) * (*R - x)) / (*R - *L));
if(*md == x) return md - a; else if(*md < x) L = md + 1; else R = md - 1;
}
return L - a;
}

评测结果