Leetcode 1137. N-th Tribonacci Number (Java)

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.

class Solution {
    public int tribonacci(int n) {
        if(n<=1) return n;
        if(n==2) return 1;
         int var2=1;
        int var1=1;
        int var0=0;
        int Tn=0;
        
     
        for(int i=3;i<=n;i++)
        {
            
            Tn=var2+var1+var0;
           
            var0=var1;
            var1=var2;
            var2=Tn;
        }
        return Tn;
    }
}