Go: package main

/*
フィボナッチ数列
*/

import (
	"bufio"
	"bytes"
	"fmt"
	"log"
	"os"
	"strconv"
	"strings"
)

func fibWithMemo(n int, memo map[int]int) int {
	if n == 0 || n == 1 {
		return 1
	}
	if val, ok := memo[n]; ok {
		return val
	}
	memo[n] = fibWithMemo(n-1, memo) + fibWithMemo(n-2, memo)
	return memo[n]
}

func fib(n int) int {
	memo := make(map[int]int)
	return fibWithMemo(n, memo)
}

func main() {
	scanner := makeScanner(1024)
	n := eGetInt(scanner)
	fmt.Println(fib(n))
}

////////////////////////////////////////////////////////////////////////////////
// ライブラリ
////////////////////////////////////////////////////////////////////////////////
func makeScanner(maxByte int) *bufio.Scanner {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Buffer(make([]uint8, 0, 8192), maxByte)
	return scanner
}
func makeWordScanner() *bufio.Scanner {
	scanner := makeScanner(8192)
	scanner.Split(bufio.ScanWords)
	return scanner
}
func eGetLine(r *bufio.Scanner) string {
	if r.Scan() {
		return r.Text()
	}
	err := r.Err()
	if err != nil {
		log.Fatal(err)
	}
	// EOF
	return ""
}
func eGetInt(r *bufio.Scanner) int {
	line := eGetLine(r)
	return eAtoi(line)
}
func eGetFields(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Fields(line)
}
func eGetInts(r *bufio.Scanner) []int {
	fields := eGetFields(r)
	ints := make([]int, len(fields))
	for i := 0; i < len(ints); i++ {
		ints[i] = eAtoi(fields[i])
	}
	return ints
}
func eGetChars(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Split(line, "")
}
func eAtoi(s string) int {
	n, err := strconv.Atoi(s)
	if err != nil {
		log.Fatal(err)
	}
	return n
}

type ints []int

func (s ints) String() string {
	var buf bytes.Buffer
	buf.WriteString("[")
	sep := ""
	for _, v := range s {
		buf.WriteString(fmt.Sprintf("%s%d", sep, v))
		sep = ", "
	}
	buf.WriteString("]")
	return buf.String()
}

func reverse(a ints) ints {
	r := make(ints, len(a))
	for i := 0; i < len(a); i++ {
		r[i] = a[len(a)-1-i]
	}
	return r
}
func max(a ints) (int, bool) {
	if len(a) == 0 {
		return 0, false
	}
	m := a[0]
	for _, e := range a {
		if e > m {
			m = e
		}
	}
	return m, true
}
func min(a []int) int {
	m := a[0]
	for _, v := range a {
		if v < m {
			m = v
		}
	}
	return m
}

func sum(a ints) int {
	if len(a) == 0 {
		return 0
	}
	sum := 0
	for _, e := range a {
		sum += e
	}
	return sum
}
func find(n int, a ints) int {
	for i, v := range a {
		if n == v {
			return i
		}
	}
	return -1
}

C++: #include <iostream>
#include <map>
using namespace std;
int memofib(int n) {
    static map<int,int> cache;
    map<int,int>::iterator it = cache.find(n);
    if( it != cache.cend() )
        return it->second;   
    int t;
    if(n==1) 
        return 1;
    else if(n==2)
        return 2;
    else
        return memofib(n-1) + memofib(n-2);
    cache.insert(std::make_pair(n, t));
    return t;
}
int main(void){
    int n;
    cin >> n ;
    cout << memofib(n) << endl;
    return 0;
}

C++: #include<iostream>
using namespace std;
int data[45];
int fib(int n){
  if(data[n]) return data[n];
  if(n==0||n==1) return data[n]=1;
  return data[n]=fib(n-1)+fib(n-2);
}
int main(){
  int n; cin>>n;
  cout<<fib(n)<<endl;
  return 0;
}

C++: #include<stdio.h>

int main(){
  int i,input,fibonacciA=1,fibonacciB=1,fibonacciC=1;
  scanf("%d",&input);
  if(input == 0 || input == 1){
    printf("%d\n",fibonacciA);
  }else{
    for(i=1;i<input;i++){
      fibonacciC = fibonacciB + fibonacciA;
      fibonacciA = fibonacciB;
      fibonacciB = fibonacciC;
    }
    printf("%d\n",fibonacciC);
  }
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
#define REP(i,s,n) for(int i=s;i<n;i++)
#define all(a) a.begin(),a.end()
typedef long long ll;
const double phi = (1 + sqrt(5)) / 2;
const double phi_ = (1 - sqrt(5)) / 2;
double fib(ll n){
    double res = pow(phi, n+1) - pow(phi_, n+1);
    return res / sqrt(5);
}
int main(){
    ll n, ans; cin >> n;
    ans = fib(n);
    cout << ans << endl;
    return 0;
}

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

int main(){
    int n; cin >> n;
    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[n] << endl;
    
    return 0;
}

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

using namespace std;

int F[50];

int fib(int n) {

	if (n == 0 || n == 1)
		return 1;
	if (F[n] != 0)
		return F[n];

	F[n] = fib(n - 1) + fib(n - 2);

	return F[n];
}

int main() {

	int n;
	scanf("%d", &n);

	for (int i = 0; i < n; ++i) {
		F[i] = 0;
	}

	cout << fib(n) << endl;

	return 0;

}

C++: #include "stdio.h"

#define MAX 50
#define INIT -1

int dp[MAX];

int fibonacci(int n){
  if(n == 0 || n == 1){
    return dp[n] = 1;
  }

  if(dp[n] >= 0 ){
    return dp[n];
  }else{
    return dp[n] = fibonacci(n-1) + fibonacci(n-2);    
  }
}


int main(void){
  
  int N;
  scanf("%d", &N);
  
  for(int i=0;i<MAX;i++){
    dp[i] = INIT;
  }
    
  printf("%d\n", fibonacci(N));

  return 0;
}

C++: #line 1 "/mnt/c/Users/leafc/dev/compro/lib/template.hpp"


#include <bits/stdc++.h>
#define REP(i, n) for (int i = 0; i < n; i++)
#define FOR(i, m, n) for (int i = m; i < n; i++)
#define ALL(v) (v).begin(), (v).end()
#define coutd(n) cout << fixed << setprecision(n)
#define ll long long int
#define vl vector<ll>
#define vi vector<int>
const int INF = 2147483647;
const ll MOD = 1000000007;

using namespace std;


#line 2 "tmp.cpp"

int main() {
  ll fib[45] = {};
  fib[0] = 1;
  fib[1] = 1;
  FOR(i, 2, 45) { fib[i] = fib[i - 1] + fib[i - 2]; }
  int n;
  cin >> n;
  cout << fib[n] << endl;
  return 0;
}

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

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

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