Maximize Sum Of Array After K Negations
<p>Given an integer array <code>nums</code> and an integer <code>k</code>, modify the array in the following way:</p>

<ul>
	<li>choose an index <code>i</code> and replace <code>nums[i]</code> with <code>-nums[i]</code>.</li>
</ul>

<p>You should apply this process exactly <code>k</code> times. You may choose the same index <code>i</code> multiple times.</p>

<p>Return <em>the largest possible sum of the array after modifying it in this way</em>.</p>

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

<pre>
<strong>Input:</strong> nums = [4,2,3], k = 1
<strong>Output:</strong> 5
<strong>Explanation:</strong> Choose index 1 and nums becomes [4,-2,3].
</pre>

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

<pre>
<strong>Input:</strong> nums = [3,-1,0,2], k = 3
<strong>Output:</strong> 6
<strong>Explanation:</strong> Choose indices (1, 2, 2) and nums becomes [3,1,0,2].
</pre>

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

<pre>
<strong>Input:</strong> nums = [2,-3,-1,5,-4], k = 2
<strong>Output:</strong> 13
<strong>Explanation:</strong> Choose indices (1, 4) and nums becomes [2,3,-1,5,4].
</pre>

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

<ul>
	<li><code>1 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
	<li><code>-100 &lt;= nums[i] &lt;= 100</code></li>
	<li><code>1 &lt;= k &lt;= 10<sup>4</sup></code></li>
</ul>
Greedy; Array; Sorting
func largestSumAfterKNegations(nums []int, k int) (ans int) {
	cnt := map[int]int{}
	for _, x := range nums {
		cnt[x]++
	}
	for x := -100; x < 0 && k > 0; x++ {
		if cnt[x] > 0 {
			m := min(k, cnt[x])
			cnt[x] -= m
			cnt[-x] += m
			k -= m
		}
	}
	if k&1 == 1 && cnt[0] == 0 {
		for x := 1; x <= 100; x++ {
			if cnt[x] > 0 {
				cnt[x]--
				cnt[-x]++
				break
			}
		}
	}
	for x, v := range cnt {
		ans += x * v
	}
	return
}