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LeetCode solutions

3952. Trionic Array I

My accepted Python solution to LeetCode problem 3952, Trionic Array I, running in 57ms.

  • Difficulty: Easy
  • Python
  • Runtime 57ms
  • Memory 17.5MB

Read the problem on LeetCode View on GitHub

The problem statement is LeetCode’s and stays on their site. What follows is my accepted solution.

Python

Accepted on LeetCode — runtime 57ms, memory 17.5MB, accepted 2026-01-02.

python
class Solution:
    def isTrionic(self, nums: List[int]) -> bool:
        n = len(nums)
        if n < 3:
            return False
        
        # Find peaks (local maxima) and valleys (local minima)
        for p in range(1, n-1):
            for q in range(p+1, n-1):
                # Check if nums[0..p] is strictly increasing
                inc1 = True
                for i in range(p):
                    if nums[i] >= nums[i+1]:
                        inc1 = False
                        break
                if not inc1:
                    continue
                
                # Check if nums[p..q] is strictly decreasing
                dec = True
                for i in range(p, q):
                    if nums[i] <= nums[i+1]:
                        dec = False
                        break
                if not dec:
                    continue
                
                # Check if nums[q..n-1] is strictly increasing
                inc2 = True
                for i in range(q, n-1):
                    if nums[i] >= nums[i+1]:
                        inc2 = False
                        break
                
                if inc1 and dec and inc2:
                    return True
        return False

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