509. Fibonacci Number
Đề Bài
The Fibonacci numbers, commonly denoted F(n) form a sequence, called the Fibonacci sequence, such that each number is the sum of the two preceding ones, starting from 0 and 1. That is,
F(0) = 0, F(1) = 1 F(n) = F(n - 1) + F(n - 2), for n > 1.
Given n, calculate F(n).
Example 1:
Input: n = 2 Output: 1 Explanation: F(2) = F(1) + F(0) = 1 + 0 = 1.
Example 2:
Input: n = 3 Output: 2 Explanation: F(3) = F(2) + F(1) = 1 + 1 = 2.
Example 3:
Input: n = 4 Output: 3 Explanation: F(4) = F(3) + F(2) = 2 + 1 = 3.
Constraints:
0 <= n <= 30
Thuật Toán & Kỹ Thuật
⏱️ Thời gian
O(n)
💾 Không gian
O(n)
Lời Giải
TypeScript
0509-fibonacci-number.ts
function fib(n: number): number {
let dp = []
dp[0] = 0
dp[1] = 1
for (let i = 2; i <= n; ++i) {
dp[i] = dp[i - 1] + dp[i - 2]
}
return dp[n]
};