Manmohan loves pattern 1

#21

before inputting col and is wrong please tell me how I can do after while loop only I am able to write int col=1; otherwise its giving me wrong ans

#22

please explain me I won’t be able to understand

#23 
int main()
{
int n;
cin>>n;
int row=1, col;
while(row<=n){
col=1;
if(row%2!=0){
while(col<=row){
cout<<1;
col=col+1;

    }
    }
    else{
        cout<<1;
        while(col<=row-2){
            cout<<0;
            col=col+1;
        }
        cout<<1;
    }
    cout<<endl;
    row=row+1;
}
return 0;
}
#24

I have declared col outside while loop here. Check it.