代码

int binary_search(const unsigned *a, int n, unsigned x)
{
unsigned long long L = 0, R = 100000000 - 1;
	for(; L < R - 7; ) {
unsigned long long md = (R * (x - a[L]) + L * (a[R] - x)) / (a[R] - a[L]);
if(a[md] == x) return md; else if(a[md] < x) L = md + 1; else R = md - 1;
}
if(a[L] == x) return L;
if(a[L+1] == x) return L+1;
if(a[L+2] == x) return L+2;
if(a[L+3] == x) return L+3;
if(a[L+4] == x) return L+4;
if(a[L+5] == x) return L+5;
if(a[L+6] == x) return L+6;
	return L+7;
}

评测结果