Is Largest Perimeter Triangle easy or hard?

Largest Perimeter Triangle is classified as an Easy problem on LeetCode with an acceptance rate above 60%. The difficulty mainly lies in recognizing that sorting allows a greedy check of adjacent triples instead of testing every combination.

Largest Perimeter Triangle Python/Java solution

The common implementation sorts the array and scans from the end to find the first valid triplet. This logic can be implemented in Python, Java, C++, C, C#, or JavaScript using built-in sorting and a single loop.

How to solve Largest Perimeter Triangle in O(n)?

A strict O(n) solution is generally not achievable because the greedy strategy depends on sorting the array. With comparison-based sorting, the best practical complexity is O(n log n). After sorting, only a single pass is needed to find the first valid triangle.

What is the best approach for Largest Perimeter Triangle?

The best approach is a greedy strategy combined with sorting. Sort the array and check triplets from the largest values downward. If nums[i-2] + nums[i-1] > nums[i], those three sides form the maximum perimeter triangle. This solution runs in O(n log n) time due to sorting and O(1) extra space.

Is Largest Perimeter Triangle asked at Google/Amazon/Meta?

Largest Perimeter Triangle appears in coding interview practice sets focused on arrays, greedy logic, and sorting. Variations of triangle inequality and greedy selection problems have been asked in interviews at companies like Amazon and Google during algorithm rounds.

What data structure is used in Largest Perimeter Triangle?

The main data structure is a simple array of integers representing side lengths. The algorithm relies on sorting the array and iterating through it while checking the triangle inequality condition.

What is the time complexity of Largest Perimeter Triangle?

The optimal solution runs in O(n log n) time because the array must be sorted first. After sorting, a single linear scan checks triangle validity in O(n). The brute force approach is O(n³) because it evaluates every combination of three sides.

Description Solution Video 11:06

976. Largest Perimeter Triangle

Easy62.1% acceptance5 companies

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.

Constraints: