# 1137. N-th Tribonacci Number

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

## Description

The Tribonacci sequence Tn is defined as follows:&#x20;

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`.

## ac

```java
```
