About implementing string flipping (with.Java)

In this article, How to Implementing string flipping (with.Java)

We’re going to go through a series of coding test problems, providing a retrospective of the problems we solved, and exploring other ways to solve them.

Let’s start with the problem

Problem

Given a string my_string and integers s and e as parameters, write a solution function that returns a string flipped from index s to index e in my_string.

Example input and output

My solution to the problem

class Solution {
    char[] arr;
    public String solution(String my_string, int s, int e) {

        arr = my_string.toCharArray();

        reverse(s,e);
        return new String(arr);
    }

    private void reverse(int startIdx, int endIdx){
        while(startIdx < endIdx){
            char temp = arr[startIdx];
            arr[startIdx++] = arr[endIdx];
            arr[endIdx--] = temp;
        }
    }
}

Solution

char[] arr;: Declares a member variable arr for converting a string to an array of characters and storing it.

public String solution(String my_string, int s, int e) : The solution function takes three parameters: my_string is the original string, s is the start index of the part to be flipped, and e is the end index of the part to be flipped.

arr = my_string.toCharArray();: Convert the given string my_string to an array of characters using the toCharArray method, and store it in arr.

reverse(s, e);: Call the reverse method to reverse the substring.

private void reverse(int startIdx, int endIdx) : The reverse method serves to reverse a portion of the character array. flip the characters between startIdx and endIdx.

while(startIdx < endIdx) : Runs a loop until startIdx is less than endIdx.

char temp = arr[startIdx];: temporarily store the character at the current startIdx position in the temp variable.

arr[startIdx++] = arr[endIdx];: Replace the character at position startIdx with the character at position endIdx, and increment startIdx to move to the next character.

arr[endIdx–] = temp;: Replace the character at position endIdx with the value stored in temp, and decrement endIdx to move to the next character.

return new String(arr);: Convert the flipped string back to a string and return it.

Have a great day!