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Formatted question description: https://leetcode.ca/all/1137.html
1137. N-th Tribonacci Number (Easy)
The Tribonacci sequence Tn is defined as follows:
T0 = 0, T1 = 1, T2 = 1, and Tn+3 = Tn + Tn+1 + Tn+2 for n >= 0.
Given n
, return the value of Tn.
Example 1:
Input: n = 4 Output: 4 Explanation: T_3 = 0 + 1 + 1 = 2 T_4 = 1 + 1 + 2 = 4
Example 2:
Input: n = 25 Output: 1389537
Constraints:
0 <= n <= 37
- The answer is guaranteed to fit within a 32-bit integer, ie.
answer <= 2^31 - 1
.
Related Topics:
Recursion
Similar Questions:
Solution 1.
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class Solution { public int tribonacci(int n) { int a = 0, b = 1, c = 1; while (n-- > 0) { int d = a + b + c; a = b; b = c; c = d; } return a; } }
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class Solution { public: int tribonacci(int n) { long long a = 0, b = 1, c = 1; while (n--) { long long d = a + b + c; a = b; b = c; c = d; } return (int) a; } };
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class Solution: def tribonacci(self, n: int) -> int: a, b, c = 0, 1, 1 for _ in range(n): a, b, c = b, c, a + b + c return a
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func tribonacci(n int) int { a, b, c := 0, 1, 1 for i := 0; i < n; i++ { a, b, c = b, c, a+b+c } return a }
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/** * @param {number} n * @return {number} */ var tribonacci = function (n) { let a = 0; let b = 1; let c = 1; while (n--) { let d = a + b + c; a = b; b = c; c = d; } return a; };
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class Solution { /** * @param Integer $n * @return Integer */ function tribonacci($n) { if ($n == 0) { return 0; } else if ($n == 1 || $n == 2) { return 1; } $dp = [0, 1, 1]; for ($i = 3; $i <= $n; $i++) { $dp[$i] = $dp[$i - 1] + $dp[$i - 2] + $dp[$i - 3]; } return $dp[$n]; } }