nth_tribonacci_number.py (575B)
| # 1137. N-th Tribonacci Number
"""
the tribonacci sequence t^n is defined as follows
t0 = 0, t1 = 1, t2 = 1, & tn+3 = tn + tn+1 + tn+2 for n >= 0
given n, return value of tn
eg.
n = 4, output: 4
t3 = 0 + 1 + 1 = 2
t4 = 1 + 1 + 2 = 4
"""
class Solution(object):
def tribonacci(self, n):
"""
:type n: int
:rtype: int
"""
a, b, c = 1, 0, 0
for _ in range(n):
a, b, c = b, c, a + b + c
return c
if __name__ == "__main__":
obj = Solution()
print(obj.tribonacci(4))
print(obj.tribonacci(25))
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