# Students-height and iq(break the server dp help)

I have written the recursive solution for the problem: CodeChef: Practical coding for everyone
I need help as I am not aware of how to apply dp to my solution. Thank you in advance!

My sol:

`````` #include<bits/stdc++.h>
#define F first
#define S second
#define PB push_back
#define er erase
#define MP make_pair
#define fastio                    \
ios_base::sync_with_stdio(0); \
cin.tie(NULL);                \
cout.tie(NULL)
const long long MOD = 1e9 + 7;
const long long INF = 1e9 + 7;
typedef long long int ll;
using namespace std;
ll lcm(ll a, ll b)
{
return (a * b) / __gcd(a, b);
}
ll power(ll a, ll b)
{
if (b == 0)
{
return 1;
}
ll curr = 1;
while (b != 1)
{
if (b % 2 != 0)
{
curr = curr * a;
a = a * a;
b = b - 1;
b = b / 2;
}
else
{
a = a * a;
b = b / 2;
}
}
return curr * a;
}
bool isprime(ll n)
{
bool flag = true;
if (n == 2 or n == 3 or n == 5 or n == 7 or n == 11)
{
flag = true;
}
else
{
for (ll i = 2; i * i <= n; i++)
{
if (n % i == 0)
{
flag = false;
break;
}
}
}
return flag;
}
// ------------------------------------------------------------------//  THE  SOLUTION STARTS FROM HERE -------------------------------------
vector<ll> h, q;
ll arr[1001][1001];
ll solve(ll i,ll n,ll pre)
{
if(i==n)
{
return 0;
}

else
{
if(pre==-1)
{
return arr[i][pre]=max(solve(i+1,n,pre),solve(i+1,n,i)+1);
}
else
{
if(h[i]>h[pre] and q[i]<q[pre])
{
return arr[i][pre]=max(solve(i + 1, n, pre), solve(i + 1, n, i) + 1);
}
else
{
return arr[i][pre]=solve(i+1,n,pre);
}
}
}
}

int main()
{
fastio;
ll t;
cin >> t;
while (t--)
{
memset(arr,-1,sizeof(arr));
q.clear();
h.clear();
ll n;
cin >> n;
for (ll i = 0; i < n; i++)
{
ll temp;
cin >> temp;
h.PB(temp);
}
for (ll i = 0; i < n; i++)
{
ll temp;
cin >> temp;
q.PB(temp);
}

cout<<solve(0,n,-1)<<endl;
}
return 0;
}
``````

I have messed storing dp sol in 2d array, ik it can be done using 1d array. I m curious to know the solution in recursive rather than iterative as i am comfortable with recursive approach.

This problem is just the Longest Increasing Subsequence problem with an additional condition. Check the solution for LIS and then try solving this problem.

Can anyone tell me whatâ€™s wrong with my code?