代码

#pragma GCC optimize("-Ofast")
#pragma GCC target("sse4")
int binary_search(const unsigned *a,const unsigned n, unsigned x)
{
	register unsigned l = 0, r = n - 1;
	for(;;) {
#define mid ((l + r) >> 1)
		if ( a[mid] == x ) return mid;
		else if (a[mid] > x ) r = mid - 1;
		else l = mid + 1;
	}
}

评测结果