Can someone tell me how to solve SUBNUMS question?
This can be solved by DIGIT-DP
Let f(x)=count of numbers <=x with 101 substring in its binary representation.
Then answer will be f®-f(l-1)
To find f(x),
First convert x to binary, then going left to right for each bit, place 0 or 1 in current position keeping current number<=x.
prev1=previous bit wrt pos
prev2=second previous bit wrt pos
issmaller=whether current number has become smaller than x or not(is still equal to x).
isfound=whether 101 has been found in current number or not
If you get prev1==0 and prev2==1 and you are placing current bit as 1, set isfound=1 (since substring 101 is found).
You can count the numbers having 101 as substring using isfound upon reaching the end of current number.
Your code is really hard to understand. Please try to rewrite the code with proper comments(if you can).