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Fibonacci Number

Problem statement​

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) = 1F(n) = F(n - 1) + F(n - 2), for n > 1.

Given n, calculate F(n).

Example 1:

Input: n = 2Output: 1Explanation: F(2) = F(1) + F(0) = 1 + 0 = 1.

Example 2:

Input: n = 3Output: 2Explanation: F(3) = F(2) + F(1) = 1 + 1 = 2.

Example 3:

Input: n = 4Output: 3Explanation: F(4) = F(3) + F(2) = 2 + 1 = 3.

Constraints:

  • 0 <= n <= 30

My solution​

/**
 * @param {number} N
 * @return {number}
 */
var fib = function(N) {
    if (N === 0) {
        return 0;
    }
    if (N === 1) {
        return 1;
    }
    
    const arr = Array.from(new Array(N + 1));
    arr[0] = 0;
    arr[1] = 1;
    for (let i = 2; i < arr.length; i++) {
        arr[i] = arr[i - 1] + arr[i - 2];
    }
    
    // console.log(arr)
    
    return arr[N];
};