1137. N-th Tribonacci Number

Description

The Tribonacci sequence T_n is defined as follows:

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

Given n, return the value of T_n.

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:

<li><code>0 &lt;= n &lt;= 37</code></li>

<li>The answer is guaranteed to fit within a 32-bit integer, ie. <code>answer &lt;= 2^31 - 1</code>.</li>