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 <= 37answer <= 2^31 - 1.
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 ;
}
}
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