Given an integer array nums, return the largest perimeter of a triangle with a non-zero area, formed from three of these lengths. If it is impossible to form any triangle of a non-zero area, return 0.
Example 1:
Input: nums = [2,1,2]
Output: 5
Explanation: You can form a triangle with three side lengths: 1, 2, and 2.
Example 2:
Input: nums = [1,2,1,10]
Output: 0
Explanation:
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.
Solution
class Solution:
def largestPerimeter(self, nums: List[int]) -> int:
nums.sort(reverse=True)
for i in range(len(nums) - 2):
if nums[i] < nums[i+1] + nums[i+2]:
return sum(nums[i:i+3])
return 0