斐波那契数列

解题思路

如果用递归会超时，所以改用数组存，或者直接输出，代码如下

题目描述

大家都知道斐波那契数列，现在要求输入一个整数n，请你输出斐波那契数列的第n项

代码实现

import java.util.Scanner;
public class Solution {
    public int Fibonacci(int n) {
        int first = 0;
        int last = 1;
        int temp = 0;
        if(n == 0)
            return first;
        if(n == 1)
            return last;
        for(int i = 2; i <= n; i++){
            temp=first+last;
            first = last;
            last = temp;
        }
        return last;
    }
    
    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        Solution solution = new Solution();
        int x = scanner.nextInt();
        System.out.println(solution.Fibonacci(x));
    }
}

用数组实现

public class Solution {
    /*
     * @param n: an integer
     * @return: an ineger f(n)
     */
        int[] a = new int[50];
    public int fibonacci(int n) {
        
        if(n<=2)
        return n-1;
        if(a[n]!=0)
        return a[n];
        else
        return a[n]=fibonacci(n-1)+fibonacci(n-2);
    }
}