找到之前的斐波那契数

原文:https://www . geesforgeks . org/find-the-previous-Fibonacci-number/

给定一个斐波那契数 N ,任务是找到前一个斐波那契数。 例:

输入: N = 8 输出: 5 5 是 8 之前的前一个斐波那契数。 输入: N = 5 输出: 3

趋近:斐波那契数列中相邻两个数的比值迅速趋近 ((1 + sqrt(5)) / 2) 。所以如果 N 除以 ((1 + sqrt(5)) / 2) 再取整,结果数就是之前的斐波那契数。 以下是上述方法的实施:

C++

// C++ implementation of the approach
#include <bits/stdc++.h>

using namespace std;

// Function to return the previous
// fibonacci number
int previousFibonacci(int n)
{
    double a = n / ((1 + sqrt(5)) / 2.0);
    return round(a);
}

// Driver code
int main()
{
    int n = 8;
    cout << (previousFibonacci(n));
}

// This code is contributed by Mohit Kumar

Java 语言(一种计算机语言,尤用于创建网站)

// Java implementation of the approach
import java.io.*;

class GFG
{

// Function to return the previous
// fibonacci number
static int previousFibonacci(int n)
{
    double a = n / ((1 + Math.sqrt(5)) / 2.0);
    return (int)Math.round(a);
}

// Driver code
public static void main (String[] args)
{
    int n = 8;
    System.out.println(previousFibonacci(n));
}
}

// This code is contributed by ajit.

Python 3

# Python3 implementation of the approach
from math import *

# Function to return the previous
# fibonacci number
def previousFibonacci(n):
    a = n/((1 + sqrt(5))/2.0)
    return round(a)

# Driver code
n = 8
print(previousFibonacci(n))

C

// C# implementation of the approach
using System;

class GFG
{

// Function to return the previous
// fibonacci number
static int previousFibonacci(int n)
{
    double a = n / ((1 + Math.Sqrt(5)) / 2.0);
    return (int)Math.Round(a);
}

// Driver code
public static void Main()
{
    int n = 8;
    Console.Write(previousFibonacci(n));
}
}

// This code is contributed by Akanksha_Rai

java 描述语言

<script>
// Javascript implementation of the approach

// Function to return the previous
// fibonacci number
function previousFibonacci(n)
{
    var a = n / ((1 + Math.sqrt(5)) / 2);
    return Math.round(a);
}

// Driver code
var n = 8;
document.write(previousFibonacci(n));

// This code is contributed by rutvik_56.
</script>

Output: 

5