Sort Array by Increasing Frequency
<p>Given an array of integers <code>nums</code>, sort the array in <strong>increasing</strong> order based on the frequency of the values. If multiple values have the same frequency, sort them in <strong>decreasing</strong> order.</p>

<p>Return the <em>sorted array</em>.</p>

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

<pre>
<strong>Input:</strong> nums = [1,1,2,2,2,3]
<strong>Output:</strong> [3,1,1,2,2,2]
<strong>Explanation:</strong> &#39;3&#39; has a frequency of 1, &#39;1&#39; has a frequency of 2, and &#39;2&#39; has a frequency of 3.
</pre>

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

<pre>
<strong>Input:</strong> nums = [2,3,1,3,2]
<strong>Output:</strong> [1,3,3,2,2]
<strong>Explanation:</strong> &#39;2&#39; and &#39;3&#39; both have a frequency of 2, so they are sorted in decreasing order.
</pre>

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

<pre>
<strong>Input:</strong> nums = [-1,1,-6,4,5,-6,1,4,1]
<strong>Output:</strong> [5,-1,4,4,-6,-6,1,1,1]</pre>

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

<ul>
	<li><code>1 &lt;= nums.length &lt;= 100</code></li>
	<li><code>-100 &lt;= nums[i] &lt;= 100</code></li>
</ul>
Array; Hash Table; Sorting
class Solution {
public:
    vector<int> frequencySort(vector<int>& nums) {
        vector<int> cnt(201);
        for (int v : nums) {
            ++cnt[v + 100];
        }
        sort(nums.begin(), nums.end(), [&](const int a, const int b) {
            if (cnt[a + 100] == cnt[b + 100]) return a > b;
            return cnt[a + 100] < cnt[b + 100];
        });
        return nums;
    }
};