2221. Find Triangular Sum of an Array

Problem

Difficulty: Medium
Tags: Array, Math, Simulation, Combinatorics, Number Theory

Intuition

the intuition to this problem was too easy. the algorithm was written on the problem, so it was really easy. I could solve it without recursion but I thought this way is much better.

Approach

i used recursion, if the array length is 1, it returns the number. and if else, we do the calculation and reduce the size of array by one.

Solution

class Solution:
    def triangularSum(self, nums: List[int]) -> int:
        if(len(nums) == 1):
            return nums[0]
        else:
            newNum = []
            for i in range(len(nums)-1):
                newNum.append((nums[i] + nums[i+1]) % 10)
            return self.triangularSum(newNum)

Complexity

Time: $O(n^2)$
Space: $O(n^2)$

Thoughts

using python really make me focus more on the problem, and it made me solve medium question really quickly.