fibonacci using recursion dynamic programming

fibonacci using recursion dynamic programming

#include <bits/stdc++.h>

#include <ext/pb_ds/assoc_container.hpp>

#include <ext/pb_ds/tree_policy.hpp>

using namespace std;

using namespace __gnu_pbds;

template <class type1>

#define ll long long int

#define endl "\n"

#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>

using ordered_multiset = tree <type1, null_type, less_equal <type1>, rb_tree_tag, tree_order_statistics_node_update>;

 //ordered_multiset <ll> kek;(declaration for multiorder set)

// ordered_set o_set;(declaration)

//kek.order_of_key(i);(strictly less then i for multi order set)

//o_set.order_of_key(5) ;(strictly less then i for multi order set)

#define yes cout << "YES\n"

#define no cout << "NO\n"

ll fibo(ll n,vector<ll>&dp)

{

    if(n<=1)

    {

          return dp[n]=n;

    }

    if(dp[n]!=-1)return dp[n];

    return dp[n]=fibo(n-1,dp)+fibo(n-2,dp);

}

int main()

{

    ios_base::sync_with_stdio(0);

    cin.tie(0);

    cout.tie(0);

   

   ll n;

   cin>>n;

   vector<ll>dp(n+1,-1);

   ll r= fibo(n,dp);

   cout<<r<<endl;

    return 0;

}