代码

int binary_search(const unsigned *a,int n,unsigned x) {
	int l=0,r=n-1,mid;
	while(1) {
		int p=a[mid=l+r>>1];
		if(p==x)
			return mid;
		else if(x<p)
			r=mid-1;
		else
			l=mid+1;
	}
	return 998244353;
}

评测结果