[LeetCode] 1137. N-th Tribonacci Number

 Problem : https://leetcode.com/problems/n-th-tribonacci-number/

Similar to Fibonacci number.

class Solution:
    def tribonacci(self, n: int) -> int:
        dp = [0, 1, 1]
      
        for i in range(3, n+1):
            dp[0], dp[1], dp[2] = dp[1], dp[2], sum(dp)
        
        return dp[n] if n < 2 else dp[2]