Method Explained-

Lets consider-

N-55

OBSERVE THE TREE AND THEN SEE THE SOLUTION

1

11 10

111 110 101 100

we will be checking Breadth First (so think what data structure we will use)

i.e queue

string ans=1;(STORE IN STRING AS ANSWER CAN BE VERY LARGE)

starting with this as number with 1 and 0 cannot start with 0

step-1)pop form q and check

if this no is divisible by N,then this is the answer

step-2)now we have to options

option1-add 1 to string=11

option2-add 0 in string-10

add them to q and repeat step 1

pop 11 and check

11 not divisilbe 2 options

110 and 111

pop 10 amd check

10 not divisible 2 options

100 and 101

then checking we get answer as 110