Here we are going to see the approach of forming a string made from the first and last 2 characters of a given string.
Input: GeeksforLazyroar Output: Geks Input: Hi, There Output: Hire
Method #1: Using list slicing
In this example, we are going to loop through the string and store the length of the string in the count variable and then make the new substring by taking the first 2 characters and the last two characters with the help of the count variable.
Python
# Taking input from the userinputString = "GeeksforLazyroar"count = 0# Loop through the stringfor i in inputString: count = count + 1newString = inputString[ 0:2 ] + inputString [count - 2: count ] # Printing the new Stringprint("Input string = " + inputString)print("New String = "+ newString) |
Input string = GeeksforLazyroar New String = Geks
Time Complexity: O(n)
Auxiliary Space: O(n)
Methods #2: Using a loop
In this example we are going to store the length of the string in a variable and break the loop if its length is less than 4 characters otherwise we will store the characters if the variable matches the defined conditions and make a new string out of it.
Python
# Taking input from userinputString = "GeeksforLazyroar"l = len(inputString)newString = ""# looping through the stringfor i in range(0, len(inputString)): if l < 3: break else: if i in (0, 1, l-2, l-1): newString = newString + inputString[i] else: continue# Printing New Stringprint("Input string : " + inputString)print("New String : " + newString) |
Input string : GeeksforLazyroar New String : Geks
Time Complexity: O(n)
Auxiliary Space: O(n)
Approach 3: Using formatted string
Algorithm to create a string made of the first and last two characters from a given string using formatted string approach:
- Initialize a variable named “inputString” and assign a string to it as input.
- Create a formatted string by slicing the first two and last two characters from the “inputString” variable and concatenating them using “{}{}” format.
- Store the formatted string in a new variable named “newString”.
Print the “inputString” and “newString” variables.
Python3
#Taking input from the userinputString = "GeeksforLazyroar"#Creating formatted stringnewString = "{}{}".format(inputString[0:2], inputString[-2:])#Printing the new Stringprint("Input string = " + inputString)print("New String = " + newString) |
Input string = GeeksforLazyroar New String = Geks
Time complexity:
The time complexity of the code is O(1) because it takes constant time to slice the input string and format the output string.
Auxiliary space:
The space complexity of the code is O(1) because it uses a constant amount of extra memory to store the input and output strings.
