Go: package main

import "fmt"

func main() {
	var n int
	fmt.Scan(&n)

	x, y := int64(0), int64(1)
	for i := 0; i < n; i++ {
		x, y = y, x+y
	}

	fmt.Println(x)
}

C++: #include<cstdio>

const int maxn = 44 + 1;
int a[maxn];

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

int getFibonacciNumber(int n) {
    return calcFibonacciNumber(n);
}

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

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

long long fibodp(int n){
    long long fibodp[200]={0};
    fibodp[0]=1;
    fibodp[1]=1;
    for(int i=2; i<=n; i++){
        fibodp[i]=fibodp[i-1]+fibodp[i-2];
    }
    return fibodp[n];
}

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

C++: #include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <cctype>
#include <string>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <algorithm>
#include <functional>

using namespace std;
using ll = long long int;
#define rep(i,n) for(int i = 0; i < n; i++)
#define FOR(i, a, b)  for(int i = (a); i < (b) ; i++)
#define pb push_back
#define SORT(v,n) sort(v, v+n)
#define ALL(x) (x).begin(),(x).end()
#define debug(x) cerr << #x << ": " << x << '\n'
#define elif else if
#define itn ll
#define int ll
const int INF = 100100100;
const int MOD = (int)1e9 + 7;
const double EPS = 1e-9;
///                →,↑,←,↓,↗,↖,↙,↘
int dx[8] = { 1, 0, -1, 0, 1, -1, -1, 1 };
int dy[8] = { 0, 1, 0, -1, 1, 1, -1, -1 };

#define MAX 3000000 
char s[MAX + 10];
int wSum[MAX + 10];
int eSum[MAX + 10];

int dp[45];

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

signed main() {
	ios::sync_with_stdio(false);
	int i, n;
	cin >> n;
	rep(i, 45) dp[i] = -1;
	cout << fibo(n) << "\n";
	return 0;
}

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

int fib() {
    int arr[N+1];
    arr[0] = 0; arr[1] = 1;

    for (int i = 2; i <= N+1; i++) {
        arr[i] = arr[i-1] + arr[i-2];
    }
    return arr[N+1];
}


int main() {

    std::scanf("%d", &N);
    std::printf("%d\n", fib());

}

C++: #include<algorithm>
#include<cstdio>
#include<cstring>
#include<iostream>
using namespace std;
#define MAX 45
int F[MAX];


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

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

    cout << F[n] << endl;

    return 0;
}

C++: #include <iostream>
#include <string>
#include <sstream>
#include <list>
#include <stack>
#include <queue>
#include <algorithm>
#include <utility>
#include <vector>
#include <map>
#include <cstring>
#include <cstdio>
#include <cmath>
 
using namespace std;
 
int f(const int);
 
int main()
{
    int N;
    int num=1,old[2]={1,1};
    cin>>N;
    for(int i=1;i<N;i++){
        num=old[0]+old[1];
        old[0]=old[1];
        old[1]=num;
    }
    cout<<num<<endl;
}

C++: #include <bits/stdc++.h>
using namespace std;
long long dp[50];
long long fib(int n){
if (n<=1) return 1;
if (dp[n]) return dp[n];
return dp[n]=fib(n-1)+fib(n-2);
}
int main(){
int n; cin>>n; cout<<fib(n)<<endl;
}

C++: #include <iostream>
#include <algorithm> // next_permutation
#include <iomanip>
#include <cmath>
#include <vector>
#include <sstream>
#include <string>
#include <cstdio>
#include <stack>
#include <queue>
#include <list>
#include <numeric> //accumulate
//#include <unordered_map> //???????????\??¢??°
#include <fstream> //ifstream, ofstream

//#define NDEBUG //NDEBUG???#include <cassert>???????????????????????????????????´???assert?????????????????????????????????NDEBUG?????????????????????????????????????????????
#include <cassert> //assert


using namespace std;

//???????????°??????TEST????????????????????¬???????????????????????????????????¢????????????
#define TEST //*******************************************************************************************************************************************
//?????????????????¨??§?????\????????????????????????????????°?????????????¨???????????????????dout???????????????????????§???????????¬??????????????????????????????????????????
//??????????????????????????????????????????????????????????§?CPU???????£??????????????????§???TLE?????????????????????????????????????????§????????¨???                           ????????????????????????cerr????????£????????????????????????????????????
#ifdef TEST
#define dout cout
#define din cin
#else
stringstream dummy; //???????????°??????dout?????????????????????????????????
#define dout dummy.str(""); dummy.clear(stringstream::goodbit); dummy //dummy?????????????????????????????????????????¨?????¢?????¢???????????????
//???????????¨??????????????????goodbit?????????????????????????????¨???????????´????????????????????????????????¨?????°?????????????????§???????????????????????????????????? http://d.hatena.ne.jp/linden/20060427/p1
#endif

//?¨??????????????????????????????????????????????????????´??????OUTPUTFILE????????????????????¬???????????????????????????????????¢????????????
//#define OUTPUTFILE "output.txt" //*******************************************************************************************************************************************
#ifdef OUTPUTFILE
#define dout outputfile //??¨????????????TLE????????§?????????dout?????¨??¨??????????????¢????????????????????????????????????????????§????¨????????????´??????????????£??????????????????????¨?????????????????????????????????????????????§?????????????????????
ofstream outputfile(OUTPUTFILE);
#define OutputFilePath "/Users/Nag/Documents/Prgm/Test/DerivedData/Test/Build/Products/Debug/output.txt"
#endif

//?¨??????\???????????????????????????????????????????????´??????INPUTFROMTEXTFILE????????????????????¬???????????????????????????????????¢????????????
//#define INPUTFILE "input.txt" //*******************************************************************************************************************************************
#ifdef INPUTFILE
#define din inputfile
ifstream inputfile(INPUTFILE);
#endif


#define disp(A) dout << #A << " = " << (A) << endl
#define disP(A) dout << setw(3) << (A) << " " // << setw(3) ??????????????\????????????
#define rep(i,a,n) for(int (i)=(a); (i)<(n); (i)++)

#define dispAll(A,n) dout << #A << " = "; rep(j, 0, (n)) {disP(A[j]);} dout << endl

typedef pair<int,int> pii;
typedef vector<int> vi;
typedef unsigned long long ll;

const int INF = 1e9-1;

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


int main() {
    int n; cin >> n;
    
    dout << fibonacci(n) << endl;
    
    
    
#ifdef INPUTFILE
    inputfile.close();
#endif
    
#ifdef OUTPUTFILE
    outputfile.close();
    cout << "\"" << OutputFilePath << "\"" << endl;
#endif
    
    return 0;
}

C++: #include<iostream>
using namespace std;
int main(){
	int n;
	cin >> n;
	int a = 1;
	int b = 1;
	for(int i=1; i<n;++i){
		int t = b;
		b = a + b;
		a = t;
	}
	cout << b << std::endl;
}

C++: #include <iostream>

using namespace std;

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

	int fib[100]={0};

	fib[0]=1;
	fib[1]=1;
	for(int i=2;i<=n;i++){
		fib[i]=fib[i-1]+fib[i-2];
	}

	cout<<fib[n]<<endl;

	return 0;
}

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

unordered_map<int,int> memo;
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)<<"\n";
}