Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	N := sc.nextInt()
	dp := make([]int, N+1)
	dp[0] = 1
	dp[1] = 1
	for i := 2; i <= N; i++ {
		dp[i] = dp[i-1] + dp[i-2]
	}

	fmt.Fprintln(wtr, dp[N])
	wtr.Flush()
}

C++: //递归求第n个斐波那契数列
#include<iostream>
using namespace std;

int F[50];
//记忆化递归生成斐波那契数列 
/*int fibonacci(int n)
{
	if(n==1||n==2)
		return F[n]=1;
	if(F[n])
		return F[n];
	else return F[n]=fibonacci(n-1)+fibonacci(n-2);
}*/
//动态规划法生成斐波那契数列
/*
int fibonacci(int n)
{
	if(n==0||n==1)
		F[n]=1;
	for(int i=2;i<n;i++)
	{
		F[i]=F[i-1]+F[i-2];		
	}	
} */
int main()
{
	int n;
	cin>>n;
	F[0]=F[1]=1;
	for(int i=2;i<=n;i++)
	{
		F[i]=F[i-1]+F[i-2];		
	}
	//int result=fibonacci(n);
	cout<<F[n]<<endl;
	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;

int main(void){
    int n;
    cin >> n;
    
    int dp[n+1];
    dp[0] = dp[1] = 1;
    for(int i = 2;i <= n;i++){
        dp[i] = dp[i-1] + dp[i-2];
    }
    cout << dp[n] << endl;
}

C++: #include <iostream>
using namespace std;

long long fib(int n){
    long long  a = 1, b = 1, tmp = 0;
    while (n--){
        tmp = a;
        a += b;
        b = tmp;
    }
    return b;
}

int main()
{
    int n = 0;
    cin >> n;
    cout << fib(n) << endl;
    
    return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
int dp[45];
int main()
{
    int n;
    cin>>n;
    dp[0]=dp[1]=1;
    for(int i=2;i<=n;i++)
    {
        dp[i]=dp[i-1]+dp[i-2];
    }
    cout<<dp[n]<<"\n";
    return 0;
}

C++: // C++ Program to find n'th fibonacci Number in 
// with O(Log n) arithmatic operations 
#include <bits/stdc++.h> 
using namespace std; 
typedef long long ll;
  
const int MAX = 1000; 

int f[MAX] = {0}; 
  

ll fib(ll n) { 
    if (n == 0) return 0; 
    if (n == 1 || n == 2) return (f[n] = 1); 

    if (f[n]) return f[n]; 
    int k = (n & 1)? (n+1)/2 : n/2; 
    f[n] = (n & 1)? (fib(k)*fib(k) + fib(k-1)*fib(k-1)) : (2*fib(k-1) + fib(k))*fib(k); 
    return f[n]; 
} 
  
/* Driver program to test above function */
int main() { 
    ll n; cin >> n; 
    cout << fib(n+1) << endl;
    return 0; 
}

C++: #include<iostream>
using namespace std;

int fib(int n){
	if(n==0||n==1){
		return 1;
	}
	return fib(n-1) + fib(n-2);
}

int main(){
	int n;
	cin>>n;
	
	cout<<fib(n)<<endl;
	
	return 0;
}

C++: #include<iostream>
using namespace std;
#define MAX 44

int fib(int i){
  if(i<=1) return 1;
  else return fib(i-1)+fib(i-2);
}

int main(){
  int n;
  cin >> n;
  cout << fib(n) << endl;

  return 0;
}

C++: #include <iostream>
#include <stdio.h>
using namespace std;

int F[45];
int fibonacci(int n)
{
    if(n==0||n==1)
        return F[n] = 1;
    else if(F[n]!=-1)
    {
        return F[n];
    }
    return F[n] = fibonacci(n-1)+fibonacci(n-2);
}
int main()
{
    int n;
    scanf("%d",&n);
    for(int i = 0; i < 45; i++)
    {
        F[i] = -1;
    }
    printf("%d\n",fibonacci(n));
}

C++: #include<iostream>
#define N 45
using namespace std;

int A[N];
int main(){
    int i,n;
    cin>>n;
    A[0]=1; A[1]=1;
    for(int i=2;i<=n;i++){
        A[i]=A[i-2]+A[i-1];
    }
    cout<<A[n]<<endl;
    return 0;
}

C++: // -*- mode:c++; coding:utf-8; c-basic-offset:2; -*-
// ALDS1_10_A: Fibonacci Number

#include <algorithm>
#include <cstdio>

#define NDEBUG
#include <cassert>

class Fibonnacci {
  static const unsigned int N = 44u;
  unsigned int n_;
  unsigned long* f_;

public:
  Fibonnacci(unsigned int n = N) : n_(std::max(1u, n))
  {
    f_ = new unsigned long[n_+1];
    f_[0] = f_[1] = 1;
    for (auto i = 2u; i <= n; ++i) {
      f_[i] = f_[i-1] + f_[i-2];
    }
  }

  ~Fibonnacci() { delete[] f_; }
  
  unsigned long operator () (unsigned int n) const
  {
    assert(n <= n_);
    return f_[n];
  }
};

int main()
{
  unsigned int n;
  std::scanf("%u", &n);
  Fibonnacci fib;
  std::printf("%lu\n", fib(n));
}

// eof

C++: #include <iostream>
using namespace std;
int solution(int n){
    if(n==0) return 1;
    if(n==1) return 1;
    int one=1,two=1,tmp;
    for(int i=1;i<n;i++){
    tmp = two;
    two = two+one;
    one = tmp;
}
    return two;
}

int main(){
    int n;
    cin>>n;
    cout<<solution(n)<<endl;
return 0;
}

C++: #include <iostream>
using namespace std;

int fib(int i) {
    if (i == 0) return 1;
    if (i == 1) return 1;
    return fib(i - 1) + fib(i - 2);
}

int main() {

    int n;
    cin >> n;

    cout << fib(n) << endl;

    return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <vector>
#include <stack>
#include <sstream>
#include <iomanip>
#include <cmath>
#include <string>
#include <cstdio>
#include <queue>
#include <list>
using namespace std;

vector<int> a(100);

int fibonacci(int n){
  if(n == 0 || n == 1){
    return 1;
  }
  if(a[n] != 0)
    return a[n];
  else
    return a[n] = fibonacci(n-2) + fibonacci(n-1);
}

int main(void){
  int n;
  cin >> n;

  cout << fibonacci(n) << endl;

  return 0;
}

C++: #include <array>
#include <iostream>

using ull = unsigned long long;
using us = unsigned short;
constexpr us n_max = 44;
ull fib(us n);

std::array<int, n_max> memo{};
/* ref: http://nonbiri-tereka.hatenablog.com/entry/2014/07/01/123518 */

int main() {
    int n;
    std::cin >> n;
    std::cout << fib(n) << std::endl;
}

ull fib(us n) {
    if (n <= 1)
        return 1;
    else if (memo[n] != 0)
        return memo[n];
    else {
        memo[n] = fib(n - 1) + fib(n - 2);
        return memo[n];
    }
}

C++: #include <bits/stdc++.h>

using namespace std;
vector<int> dp(50, -1);

int fib(int n) {
    if (0 <= dp[n])
        return dp[n];
    if (n == 0 || n == 1)
        return dp[n] = 1;
    return dp[n] = fib(n - 1) + fib(n - 2);
}

int main(void) {
    int n;
    scanf("%d", &n);

    cout << fib(n) << endl;
}

C++: #include <iostream>
#include <vector>
using namespace std;

int main() {
   int N; cin >> N;
   vector<int>F(50);
   F[0] = F[1] = 1;
   for (int i = 2; i <= N; i++) F[i] = F[i - 1] + F[i - 2];
   
   cout << F.at(N) << endl;
}

C++: #include "bits/stdc++.h"
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;

using ll = long long;

int main() {
    int n;
    cin >> n;
    vector<ll> f(n + 1, 1);
    rep(i, n - 1) f[i + 2] = f[i] + f[i + 1];
    cout << f[n] << "\n";
}