剑指offer、牛客-斐波那契数列

非递归：时间复杂度为O(n)

public class Solution {
    public int Fibonacci(int n) {
        int[] result = {0,1};
		if(n <= 0)
            return result[0];
        if(n == 1)
            return result[1];
        int sum = 0;
        for(int i = 2; i <= n; i++){
            sum = result[0] + result[1];
            result[0] = result[1];
            result[1] = sum;
        }
        return sum;
        
    }
}