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`

.

Solution: