class Solution { public int tribonacci(int n) { if (n == 0) return 0; else if (n == 1) return 1; else if (n == 2) return 1; int t0 = 0; int t1 = 1; int t2 = 1; for (int i = 3; i <= n; i++) { int tmpT1 = t1; int tmpT2 = t2; t2 = t0 + t1 + t2; t1 = tmpT2; t0 = tmpT1; } return t2; } }