n-th-tribonacci-number

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1137. N-th Tribonacci Number (Easy)

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:

• 0 <= n <= 37
• The answer is guaranteed to fit within a 32-bit integer, ie. answer <= 2^31 - 1.

Related Topics

[Recursion]

Similar Questions

1. Climbing Stairs (Easy)

Hints

Hint 1

Make an array F of length 38, and set F[0] = 0, F[1] = F[2] = 1.

Hint 2

Now write a loop where you set F[n+3] = F[n] + F[n+1] + F[n+2], and return F[n].