Leetcode 2221. Find Triangular Sum of an Array [Python]

其实是个很好的递归题目，一眼看着咩反应过来，还是自己弱的问题。。

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

一个朴素的会TLE的版本。

class Solution:
    def triangularSum(self, nums: List[int]) -> int:
        if len(nums) == 1:return nums[0]
        stack = []
        for num in nums:
            stack.append(num)
        newstack = []
        for _ in range(len(nums)-1):
            while stack:
                a1 = stack.pop(0)
                a2 = stack.pop(0)  
                cursum = (a1 + a2)%10
                newstack.append(cursum)
                if len(stack):
                    stack = [a2]+stack
            stack = newstack
            newstack = []    
        return stack[0]