Merge pull request #560 from Karnak123/1137-N-th-Tribonacci-Number

added solution to leetcode problem 1137

Author: vJechsmayr

LeetCode/1137_N_th_Tribonacci_Number.py

@@ -0,0 +1,14 @@
+class Solution:
+ def tribonacci(self, n: int) -> int:
+ a, b, c = 0, 1, 1
+ if n == 0:
+ return 0
+ elif n == 1 or n == 2:
+ return 1
+ else:
+ for _ in range(n - 2):
+ temp = a + b + c
+ a = b
+ b = c
+ c = temp
+ return temp