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++: using namespace std;

int dp[44];

int fib(int n) {
	if (dp[n] != -1)return dp[n];
	int res;

	if (n == 0 || n == 1) {
		res = 1;
	}
	else {
		res = fib(n - 1) + fib(n - 2);
	}

	dp[n] = res;
	return res;
}

int main() {
	for (int i = 0; i < 44; i++) {
		dp[i] = -1;
	}
	int n;
	cin >> n;
	cout << fib(n);

	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define REP(i,n) for (int i = 0; i < n; i++)
typedef long long ll;
// Welcome to my source code!

int F[45] = {};

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

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

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 <cstdint>

using namespace std;

#define MEMO_SIZE 45
int64_t memo[MEMO_SIZE];

void fib_init()
{
  for (uint32_t i = 0; i < MEMO_SIZE; i++) {
    memo[i] = -1;
  }
}

uint32_t fib(uint32_t i)
{
  if (i == 0) {
    return memo[0] = 1;
  } else if (i == 1) {
    return memo[1] = 1;
  } else {
    if (memo[i] != -1)
      return memo[i];
    else {
      return memo[i] = fib(i - 1) + fib(i - 2);
    }
  }
}

#include <iostream>

int32_t main()
{
  fib_init();
  uint32_t i;
  cin >> i;
  cout << fib(i) << endl;
  return 0;
}

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

unordered_map<int,int> memo;
constexpr int fib(int n){
    if(n<2) return 1;
    if (not memo.count(n)) memo[n] = fib(n-1)+fib(n-2);
    return memo[n];

}

int main(void){cin.tie(0);ios::sync_with_stdio(false);
    int n; cin>>n;
    cout<<fib(n);
}

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

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

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

using namespace std;

#define FOR(i,s,e) for((i)=(s);(i)<(int)(e);(i)++)
#define REP(i,e) FOR(i,0,e)

#define all(o) (o).begin(), (o).end()
#define psb(x) push_back(x)
#define mp(x,y) make_pair((x),(y))

typedef long long ll;
typedef pair<int, int> PII;

const double EPS = 1e-10;

const int M = 2;
int a[M][M], b[M][M], w[M][M];
int n;

//???????£?
//recursive function(with/without memo)

void multiple_mat_ab_b() {
  int i, j, k;
  memset(w, 0, sizeof(w));
  for (i=0; i<M; i++)
    for (j=0; j<M; j++)
      for (k=0; k<M; k++)
        w[i][j] += a[i][k]*b[k][j];

  for (i=0; i<M; i++)
    for (j=0; j<M; j++)
        b[i][j] = w[i][j];
}

void multiple_mat_aa_a() {
  int i, j, k;
  memset(w, 0, sizeof(w));
  for (i=0; i<M; i++)
    for (j=0; j<M; j++)
      for (k=0; k<M; k++)
        w[i][j] += a[i][k]*a[k][j];

  for (i=0; i<M; i++)
    for (j=0; j<M; j++)
        a[i][j] = w[i][j];
}

void pow_mat_a(int k) {
  a[0][0] = a[0][1] = a[1][0] = 1;
  a[1][1] = 0;

  b[0][0] = b[1][1] = 1;
  b[0][1] = b[1][0] = 0;

  while (k) {
    if (k & 1) multiple_mat_ab_b();
    multiple_mat_aa_a();
    k >>= 1;
  }
}

int main() {
  scanf("%d ", &n);
  pow_mat_a(n);
  printf("%d\n", b[1][0]+b[1][1]);

	return 0;
}

C++: #include<iostream>

using namespace std;

int fib(int n);

int memo[45];

int main(){
  int n;

  //??\???
  cin >> n;

  //??????
  cout << fib(n) << endl;

  return 0;
}

int fib(int n){

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

C++: #include <iostream>

using namespace std;

int fibdp[50];

int fib(int n){
	if(n == 1 || n == 0){
		return 1;
	}
	if (fibdp[n] != 0){
		return fibdp[n];
	}
	return fibdp[n] = fib(n - 1) + fib(n - 2);
}
int main(){
	int n;

	cin >> n;

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

C++: #include <iostream>
#include <cstdio>
#include <climits>
#include <cmath>
#include <algorithm>
#include <utility>
#include <vector>
#include <string>

#define MAX 200000
#define INFTY 1<<30

using namespace std;

int main()
{
  int n; cin >> n;
  int F[MAX];
  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 <stdio.h>

int main() {
    int n;
    scanf("%d", &n);
    int F[50];
    F[0] = 1;
    F[1] = 1;
    for(int i=2; i<50; i++) F[i] = F[i-2] + F[i-1];
    
    printf("%d\n", F[n-1]);
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define MAX_N 10000
int dp[MAX_N];
int fib(int n){
    dp[0]=1;
    dp[1]=1;
    for(int i=2;i<=n;i++){
        dp[i]=dp[i-1]+dp[i-2];
    }
    return dp[n];
}
int main(){
    int n;
    cin>>n;
    int ans=fib(n);
    cout<<ans<<endl;
    return 0;
}