Software Developer

A few days back, Ninja encountered a string containing characters from ‘A’ to ‘Z’ which indicated a secret message. For security purposes he encoded each character of the string to its numeric value, that is, A = 1, B = 2, C = 3, till Z = 26 and combined them as a single sequence (SEQ) of digits of length N. Let's say the message was "LA", Ninja encoded it as 121 for L=12 and A=1.

Today, when he read the encoded secret message, he realised that he was not able to decode the original string. So, the Ninja is wondering in how many ways he can decode the numeric sequence to some valid string.

A valid string is a string with characters from A to Z and no other characters.

Example:

Let the encoded sequence be 121,

The first way to decode 121 is:
1 = A
2 = B
1 = A
Thus, the decoded string will be ABA.

The second way to decode 121 is:
12 = L
1 = A
Thus, the decoded string will be LA.

The third way to decode 121 is:
1 = A
21 = U
Thus, the decoded string will be AU.

So, there will be 3 ways to decode the sequence 121 i.e. [(ABA), (LA), (AU)].

Note:

The input sequence will always have at least 1 possible way to decode.    

As the answer can be large, return your answer modulo 10^9  + 7.

Follow Up:

Can you solve this using constant extra space?

Sanyam has ‘N’ candies, he wants to distribute that into ‘K’ of his friends. He made his ‘K’ friends stand in line, in increasing order of his likeness. Not being so smart he gives 1 candy to the first friend, 2 to the second person, and so on till the kth person. In the next turn, the first person gets ‘K + 1’ candies, the second person gets ‘K + 2’ candies, and so on.

While distributing the candies, if at a turn, the number of candies to be given to a friend is less than the required candies, then that friend gets all the remaining candies and Sanyam stops the distribution.

Your task is to find the total number of candies every person has at the end.