leetcode 1137 python

题目要求： https://leetcode-cn.com/problems/n-th-tribonacci-number/submissions/ **

动态规划的两种解题思路：向上递推和向下递归

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class Solution: def tribonacci(self, n: int) -> int: dict1 = {0: 0, 1: 1, 2: 1} for i in range(3, 38): res = dict1[i-1] + dict1[i-2] + dict1[i-3] dict1[i] = res return dict1[n]