# [Swift Weekly Contest 118]LeetCode976. 三角形的最大周长 | Largest Perimeter Triangle

Given an array `A` of positive lengths, return the largest perimeter of a triangle with non-zero area, formed from 3 of these lengths.

If it is impossible to form any triangle of non-zero area, return `0`

Example 1:

```Input: [2,1,2]
Output: 5
```

Example 2:

```Input: [1,2,1]
Output: 0
```

Example 3:

```Input: [3,2,3,4]
Output: 10
```

Example 4:

```Input: [3,6,2,3]
Output: 8 ```

Note:

1. `3 <= A.length <= 10000`
2. `1 <= A[i] <= 10^6`

```输入：[2,1,2]

```

```输入：[1,2,1]

```

```输入：[3,2,3,4]

```

```输入：[3,6,2,3]

1. `3 <= A.length <= 10000`
2. `1 <= A[i] <= 10^6`

324ms

``` 1 class Solution {
2     func largestPerimeter(_ A: [Int]) -> Int {
3         var A = A.sorted(by:<)
4         var n = A.count
5         for i in stride(from:n-3,through:0,by:-1)
6         {
7             if A[i] + A[i+1] > A[i+2]
8             {
9                 return A[i] + A[i+1] + A[i+2]
10             }
11         }
12         return 0
13     }
14 }```

[Swift Weekly Contest 118]LeetCode976. 三角形的最大周长 | Largest Perimeter Triangle

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