Minimum Number of Operations to Make Arrays Similar
<p>You are given two positive integer arrays <code>nums</code> and <code>target</code>, of the same length.</p>

<p>In one operation, you can choose any two <strong>distinct</strong> indices <code>i</code> and <code>j</code> where <code>0 &lt;= i, j &lt; nums.length</code> and:</p>

<ul>
	<li>set <code>nums[i] = nums[i] + 2</code> and</li>
	<li>set <code>nums[j] = nums[j] - 2</code>.</li>
</ul>

<p>Two arrays are considered to be <strong>similar</strong> if the frequency of each element is the same.</p>

<p>Return <em>the minimum number of operations required to make </em><code>nums</code><em> similar to </em><code>target</code>. The test cases are generated such that <code>nums</code> can always be similar to <code>target</code>.</p>

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

<pre>
<strong>Input:</strong> nums = [8,12,6], target = [2,14,10]
<strong>Output:</strong> 2
<strong>Explanation:</strong> It is possible to make nums similar to target in two operations:
- Choose i = 0 and j = 2, nums = [10,12,4].
- Choose i = 1 and j = 2, nums = [10,14,2].
It can be shown that 2 is the minimum number of operations needed.
</pre>

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

<pre>
<strong>Input:</strong> nums = [1,2,5], target = [4,1,3]
<strong>Output:</strong> 1
<strong>Explanation:</strong> We can make nums similar to target in one operation:
- Choose i = 1 and j = 2, nums = [1,4,3].
</pre>

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

<pre>
<strong>Input:</strong> nums = [1,1,1,1,1], target = [1,1,1,1,1]
<strong>Output:</strong> 0
<strong>Explanation:</strong> The array nums is already similiar to target.
</pre>

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

<ul>
	<li><code>n == nums.length == target.length</code></li>
	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
	<li><code>1 &lt;= nums[i], target[i] &lt;= 10<sup>6</sup></code></li>
	<li>It is possible to make <code>nums</code> similar to <code>target</code>.</li>
</ul>
Greedy; Array; Sorting
func makeSimilar(nums []int, target []int) int64 {
	sort.Ints(nums)
	sort.Ints(target)
	a1, a2, b1, b2 := []int{}, []int{}, []int{}, []int{}
	for _, v := range nums {
		if v%2 == 0 {
			a1 = append(a1, v)
		} else {
			a2 = append(a2, v)
		}
	}
	for _, v := range target {
		if v%2 == 0 {
			b1 = append(b1, v)
		} else {
			b2 = append(b2, v)
		}
	}
	ans := 0
	for i := 0; i < len(a1); i++ {
		ans += abs(a1[i] - b1[i])
	}
	for i := 0; i < len(a2); i++ {
		ans += abs(a2[i] - b2[i])
	}
	return int64(ans / 4)
}

func abs(x int) int {
	if x < 0 {
		return -x
	}
	return x
}