Largest Perimeter Triangle
<p>Given an integer array <code>nums</code>, return <em>the largest perimeter of a triangle with a non-zero area, formed from three of these lengths</em>. If it is impossible to form any triangle of a non-zero area, return <code>0</code>.</p>

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

<pre>
<strong>Input:</strong> nums = [2,1,2]
<strong>Output:</strong> 5
<strong>Explanation:</strong> You can form a triangle with three side lengths: 1, 2, and 2.
</pre>

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

<pre>
<strong>Input:</strong> nums = [1,2,1,10]
<strong>Output:</strong> 0
<strong>Explanation:</strong> 
You cannot use the side lengths 1, 1, and 2 to form a triangle.
You cannot use the side lengths 1, 1, and 10 to form a triangle.
You cannot use the side lengths 1, 2, and 10 to form a triangle.
As we cannot use any three side lengths to form a triangle of non-zero area, we return 0.
</pre>

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

<ul>
	<li><code>3 &lt;= nums.length &lt;= 10<sup>4</sup></code></li>
	<li><code>1 &lt;= nums[i] &lt;= 10<sup>6</sup></code></li>
</ul>
Greedy; Array; Math; Sorting
func largestPerimeter(nums []int) int {
	sort.Ints(nums)
	for i := len(nums) - 1; i >= 2; i-- {
		c := nums[i-1] + nums[i-2]
		if c > nums[i] {
			return c + nums[i]
		}
	}
	return 0
}