Problem in understanding the problem

#1

i did not understand the problem and the approach behimd it

#2

Hello @goelsparsh277,

In this question you have to find how many CB numbers you can generate from a given number.
Description of CB numbers are given in the question.

Approach:

  1. check for all sub-strings of the given string of digits, starting from all strings of length 1 and then gradually checking for the strings of increasing size:
    1.1. check if the sub-string is CB number: for this, create a function
    1.1.1. if sub-string is 1 or 0 return false.
    1.1.2. if sub-string is any of the {2,3,5,7,11,13,17,19,23,29}, then return true.
    1.1.3. if sub-string is divisible by any of the {2,3,5,7,11,13,17,19,23,29}, then return false.
    1.1.4. return false

    1.2. now if it is a substring:
    1.2.1. call a function that marks the index as visited for indexes which are part of that CB number.

    1.3. increment the count for CB number.

  2. Print the count

Hope, this would help.
If you still have any issue, feel free to ask.
Give a like if you are satisfied.

#3

#include #include #include<math.h> #include using namespace std; bool iscb(long long int a){ if(a==1){ return false; } if(a==0){ return false; } if(a==2){ return true; } for(int i=2;i<=sqrt(a);i++){ if(a%i==0){ return false; } } return true; } int main() { int n,count=0; cin>>n; string s; cin>>s; for(int i=0;i<s.size();i++){ for(int j=1;j<=s.size()-i;j++){ string ne=s.substr(i,j); stringstream geek(ne); long long int x; geek>>x; if(iscb(x)){ cout<<x<<" "; count++; i=j-1+i; break; } } } cout<<count; return 0; }

#4

i cant find the prolem

#5
#6

Hello @goelsparsh277,

Mistakes in your code:

  1. There is no code for the point 1.1.2. of my previous reply.
    You are returning true only for a=2 in that point.

  2. Missing logic for point 1.2.1.
    Reason to use it:
    To avoid using the element present on the same index in two different CB numbers.

  3. You have to first check for all sub-strings of length 1 and then increment the size one by one of the sub-strings.
    Reason:
    You have to maximize the count for CB number.

Corrected code:

Hope, this would help.
Give a like if you are satisfied.

#7

okay got it , thank you sir

#8

Anytime @goelsparsh277,

Please, mark it as resolved if you haven’t.