➤ Problem Link : 1288C. Two Arrays
✅ C++ Solution :
#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define mod 1000000007
int main()
{
int n,m;
cin>>n>>m;
ll dpA[m+1][n+1],dpB[m+1][n+1];
memset(dpA,0,sizeof(dpA));
memset(dpB,0,sizeof(dpB));
for(int i=1;i<=m;i++)
{
for(int j=1;j<=n;j++)
{
if(i==1)
{
dpA[i][j]=1;
continue;
}
for(int k=1;k<=j;k++)
dpA[i][j]=(dpA[i][j]+dpA[i-1][k])%mod;
}
}
for(int i=1;i<=m;i++)
{
for(int j=1;j<=n;j++)
{
if(i==1)
{
dpB[i][j]=1;
continue;
}
for(int k=j;k<=n;k++)
dpB[i][j]=(dpB[i][j]+dpB[i-1][k])%mod;
}
}
// cout<<dpA[n][1]<<" "<<dpA[n][2]<<endl;
// cout<<dpB[n][1]<<" "<<dpB[n][2]<<endl;
ll ans=0;
ll cnt;
for(ll i=1;i<=n;i++)
{
for(ll k=i;k<=n;k++)
{
cnt=(dpA[m][i]*dpB[m][k])%mod;
// cout<<cnt<<endl;
ans=(ans+cnt)%mod;
}
}
cout<<ans;
}
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I am a Member Technical at D.E. Shaw India Pvt. Ltd. CodingWithArt is a blog where you find tricks and solutions to challenging coding and development problems. I aim to build a universal tech platform for every enthusiast out there.