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.

class Solution {
    int dp[38] = {0,};
public:
    int tribonacci(int n) {
        if(n <= 2) return n ? 1 : 0;
        if(dp[n]) return dp[n];
        return dp[n] = tribonacci(n-1) + tribonacci(n-2) + tribonacci(n-3);
    }
};