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:
3 <= A.length <= 10000
1 <= A[i] <= 10^6
class Solution:
    def largestPerimeter(self, A: List[int]) -> int:
        if len(A) < 3:
            return 0
        A.sort()
        counter = 3
        perimeter = 0
        while counter <= len(A):
            
            a = A[counter -3]
            b = A[counter - 2]
            c = A[counter - 1]
            
            if a +b <= c:
                counter += 1
                continue
            elif b +c <= a:
                counter += 1
                continue
            elif c + a <= b:
                counter += 1
                continue
            perimeter = a+b+c
            if a+b+c > perimeter:
                perimeter= a+b+c
                
            counter += 1
        return perimeter
class Solution:
    def largestPerimeter(self, A: List[int]) -> int:
        if len(A) < 3:
            return 0
        A.sort()
        counter = 3
        perimeter = 0
        while counter <= len(A):
            
            a = A[counter -3]
            b = A[counter - 2]
            c = A[counter - 1]
            
            if a +b <= c:
                counter += 1
                continue
            elif b +c <= a:
                counter += 1
                continue
            elif c + a <= b:
                counter += 1
                continue
            perimeter = a+b+c
            if a+b+c > perimeter:
                perimeter= a+b+c
                
            counter += 1
        return perimeter