1137. N-th Tribonacci Number.java

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