Day_30_1137. N-th Tribonacci Number.cpp

class Solution {
public:
    int tribonacci(int n) {
        vector<int> fib(40,0);
        fib[0] = 0 ;
        fib[1] = 1 ;
        fib[2] = 1 ;
        for ( int i = 3 ; i <= n ; i++ ) {
            fib[i] = fib[i-1] + fib[i-2] + fib[i-3] ;
        }
        return fib[n];
    }
};