Search⌘ K
AI Features
Home
Courses
Grokking the Coding Interview Patterns in C++

N-th Tribonacci Number

Understand how to compute the N-th Tribonacci number by applying dynamic programming concepts. Explore the problem definition, constraints, and iterative reasoning to build an efficient solution in C++. This lesson helps you master a classic coding interview problem useful for technical interviews.

We'll cover the following...

Statement

Given a number n, calculate the corresponding Tribonacci number. The Tribonacci sequence TnT_n is defined as:

T0=0, T1=1, T2=1T_0 = 0,\space T_1 = 1,\space T_2 = 1, and  Tn+3=Tn+Tn+1+Tn+2, \space T_{n+3} = T_n + T_{n+1} + T_{n+2},\space for n>=0n >= 0

The input number, n, is a non-negative integer.

Constraints:

  • 0≤0 \leq n ≤37\leq 37
  • The answer is guaranteed to fit within a 32-bit integer, i.e., answer ≤231−1\leq 2 ^{31} - 1

Examples

Understand the problem

Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

N-th Tribonacci Number

1.

What is the 5th Tribonacci number?

A.

5

B.

7

C.

15

D.

4

1 / 3

Figure it out!

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Sequence - Vertical
Drag and drop the cards to rearrange them in the correct sequence.
1
2
3

Try it yourself

Implement your solution in the following coding playground:

C++
usercode > main.cpp
int FindTribonacci(int n)

{

    // Replace this placeholder return statement with your code

    return -1;

}
N-th Tribonacci Number