What need to fill in len2 and how?

#1

Comment body goes here.

#2

Bro pls tell what is gone wrong in this code ?
for(int i=0;i<n;i++)
{
for(int j=0;j<=i;j++)
{
if(i==j || j==0)
{
B[i][j]==1;
}

        else
        {
            B[i][j]=B[i-1][j-1]+B[i-1][j];
        }
    }
}