代码

int binary_search(const unsigned *a, int n, unsigned x)
{
	int l = 0, r = n - 1, mid;
	while (a[r] != x)
		mid = (l + (r - l) * (long long)(x - a[l]) / (a[r] - a[l])), a[mid] < x ? (l = mid + 1) : (r = mid);
	return r;
}

评测结果