### LeetCode Challenge #1137. N-th Tribonacci Number

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`.
##### 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 ;
}
}
```
```
###### 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;
}
};
```
```