Fibonacci Number

class Solution:
    def fib(self, n: int) -> int:
        if n < 2:
            return n

        a, b = 0, 1
        for _ in range(2, n + 1):
            a, b = b, a + b
        return b

class Solution {
public:
    int fib(int n) {
        if (n < 2) {
            return n;
        }

        int a = 0;
        int b = 1;
        for (int i = 2; i <= n; i++) {
            int next = a + b;
            a = b;
            b = next;
        }
        return b;
    }
};

function fib(n: number): number {
    if (n < 2) {
        return n;
    }

    let a = 0;
    let b = 1;
    for (let i = 2; i <= n; i++) {
        const next = a + b;
        a = b;
        b = next;
    }
    return b;
}