<p>Given an integer array <code>nums</code>, return<em> an integer array </em><code>counts</code><em> where </em><code>counts[i]</code><em> is the number of smaller elements to the right of </em><code>nums[i]</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> nums = [5,2,6,1]
<strong>Output:</strong> [2,1,1,0]
<strong>Explanation:</strong>
To the right of 5 there are <b>2</b> smaller elements (2 and 1).
To the right of 2 there is only <b>1</b> smaller element (1).
To the right of 6 there is <b>1</b> smaller element (1).
To the right of 1 there is <b>0</b> smaller element.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> nums = [-1]
<strong>Output:</strong> [0]
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> nums = [-1,-1]
<strong>Output:</strong> [0,0]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
</ul>


def count_smaller(nums, counts, offset, n):
    if n == 1:
        return [offset]
    else:
        split_idx = n // 2
        left_sorted = count_smaller(nums, counts, offset, split_idx)
        right_sorted = count_smaller(nums, counts, offset + split_idx, n-split_idx)
        merged = []
        left_idx = 0
        right_idx = 0
        while left_idx < len(left_sorted) or right_idx < len(right_sorted):
            if left_idx == len(left_sorted) or (right_idx < len(right_sorted) and nums[left_sorted[left_idx]] > nums[right_sorted[right_idx]]):
                merged.append(right_sorted[right_idx])
                right_idx += 1
            elif right_idx == len(right_sorted) or nums[left_sorted[left_idx]] <= nums[right_sorted[right_idx]]:
                merged.append(left_sorted[left_idx])
                counts[left_sorted[left_idx]] += right_idx
                left_idx += 1
        return merged


class Solution:
    def countSmaller(self, nums: List[int]) -> List[int]:
        counts = [0 for _ in range(len(nums))]
        count_smaller(nums, counts, 0, len(nums))
        return counts

41053