[E].[J].1137.N-thTribonacciNumber

class Solution {
    public int tribonacci(int n) {
        if (n == 0) return 0;
        if (n == 1) return 1;
        int[] arr = new int[n+1];
        arr[0] = 0;
        arr[1] = 1;
        arr[2] = 1;
        for (int i = 3; i <= n; i++) {
            arr[i] = arr[i-1] + arr[i - 2] + arr[i - 3]; 
        }
        return arr[n];
    }
}