1137. N-th Tribonacci Number

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

Description

The Tribonacci sequence Tn is defined as follows:

T0 = 0, T1 = 1, T2 = 1, and Tn+3 = Tn + Tn+1 + Tn+2 for n >= 0.

Given n, return the value of Tn.

Example 1:

**Input:** n = 4
**Output:** 4
**Explanation:**
T\_3 = 0 + 1 + 1 = 2
T\_4 = 1 + 1 + 2 = 4

Example 2:

**Input:** n = 25

**Output:** 1389537

Constraints:

• 0 <= n <= 37

• The answer is guaranteed to fit within a 32-bit integer, ie. answer <= 2^31 - 1.

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