Decrypt a string according to given rules
Given encrypted string str, the task is to decrypt the given string when the encryption rules are as follows:
- Start with the first character of the original string.
- In every odd step, append the next character to it.
- In every even step, prepend the next character to the encrypted string so far.
For example, if str = “geeks” then the encrypted string will be,
g -> ge -> ege -> egek -> segek
Input: str = “segosegekfrek”
Input: str = “vrstie”
Approach: The steps that are given to encrypt the string can be followed in reverse order to obtain the original string. There will be two conditions to obtain the original string:
- If the string is of odd length, in odd step add the characters from the back in the resultant string, else add from the front.
- If the string is of even length, in odd step add characters from the front and add characters from back in even step.
The reverse of the resultant string thus obtained is the original string which was encrypted.
Below is the implementation of the above approach:
Below is Python’s implementation.
segek segosegekfrek vrstie iuthskviacitr iuthadpamcitr nrechakrak hreechakrat ecdcoehf aimIaVks oeaoolHelHwryu gidoeaawhtryuon geeks geeksforgeeks strive vikaschitturi padmachitturi hackerrank hackerearth IamVikas HelloHowareyou whatareyoudoing
Approach: Using 2 pointers
geeksforgeeks strive geeks