LeetCode Challenge #1137. N-th Tribonacci Number

Day 4 of 100 Days LeetCode Challenge

Question 59 of 75 - LeetCode Weekly Challenge

LeetCode Challenge #1137. N-th Tribonacci Number

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.

Java Video Solution

C++ Video Solution

Java Solution

				
					class Solution {
    public int tribonacci(int n) {
        if( n==0){
            return 0;
        }else if ( n==1 || n==2){
            return 1 ;
        }

        int ft = 0 ;
        int st = 1 ;
        int tt = 1 ;

        for(int i=1 ; i<=n;i++){
            int fot = ft + st + tt ;
            ft = st ;
            st = tt ;
            tt = fot ;
        }

        return ft ;
    }
}

Flowchart of Java Solution

C++ Solution

				
					class Solution {
public:
    int tribonacci(int n) {
        if(n<3)return (n!=0);
        int first=0;
        int second=1;
        int third=1;
        int fourth=0;

        for(int i=3; i<=n; i++)
        {
            fourth=first+second+third;
            first=second;
            second=third;
            third=fourth;
        }
        return third;
    }
};

Day 4 of 100 Days LeetCode Challenge

Question 59 of 75 - LeetCode Weekly Challenge

LeetCode Challenge #1137. N-th Tribonacci Number

Java Video Solution

C++ Video Solution

Java Solution

Flowchart of Java Solution

C++ Solution

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