Lets Code Everyday - Day 10

Hello there 👋, enthusiasts.

Between day one and day ten, a lot of things changed. There is a noticeable difference in my thought process when solving a problem, and to be specific, I am giving it a try at least now if I see a problem rather than leaving it.

Maintain consistency, and things will undoubtedly change.

Question - 10 :

You own a Goal Parser that can interpret a string command. The command consists of an alphabet of "G", "()" and/or "(al)" in some order. The Goal Parser will interpret "G" as the string "G", "()" as the string "o", and "(al)" as the string "al". The interpreted strings are then concatenated in the original order.

Given the string command, return the Goal Parser*'s interpretation of* command.

 Example 1:

Input: command = "G()(al)"
Output: "Goal"
Explanation: The Goal Parser interprets the command as follows:
G -> G
() -> o
(al) -> al
The final concatenated result is "Goal".

Example 2:

Input: command = "G()()()()(al)"
Output: "Gooooal"

Example 3:

Input: command = "(al)G(al)()()G"
Output: "alGalooG"

First approach:

class Solution {
   public String interpret(String command) {
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < command.length(); i++) {
        if (command.charAt(i) == 'G') {
            sb.append('G');
        } else if (command.startsWith("()", i)) {
            sb.append('o');
            i++;
        } else if (command.startsWith("(al)", i)) {
            sb.append("al");
            i += 3;
        }
    }
    return sb.toString();
}
}

Step-by-step explanation:

1. The interpret method takes a string command as input.

2. Create a new StringBuilder object called sb. This object will be used to build the output string as the method iterates through the input string.

3. Use a for loop to iterate through each character in the command string. The loop will continue until the end of the string is reached.

4. Within the loop, use an if-else structure to handle each type of command character. If the current character is 'G', append it to the StringBuilder object.

5. If the current character is '(', then check the next character. If the next character is ')', append 'o' to the StringBuilder object and increment i by 1 to skip the next character.

6. If the current character is '(' and the next three characters are 'al)', append 'al' to the StringBuilder object and increment i by 3 to skip the next two characters.

7. When the loop has finished iterating through all the characters in the command string, return the final output string by converting the StringBuilder object to a String using the toString() method.

the time complexity of the interpret method is O(n), and the space complexity is also O(n).

Second approach:

class Solution {
    public String interpret(String command) {
      return command.replace("()","o").replace("(al)","al");
    }
}

Step-by-step explanation:

1. The interpret method takes a string command as input.

2. The replace method is called on the input string command with the arguments "()" and "o". This replaces all occurrences of "()" in the string with "o". The resulting string is returned.

3. The replace method is called again on the updated string returned from step 2, with the arguments "(al)" and "al". This replaces all occurrences of "(al)" in the string with "al". The final updated string is returned.

4. The interpret method returns the final updated string as the output.

The time complexity of the interpret method using replace is O(n), where n is the length of the input string, and the space complexity is also O(n) due to the creation of a new string object.

Conclusion:

Both codes achieve the same functionality of interpreting a string of commands and returning the resulting output string.

In terms of time and space complexity, both codes have a time complexity of O(n), where n is the length of the input string. However, the first code uses a StringBuilder object to append and modify the output string, which could potentially be more memory efficient than creating multiple new string objects using replace in the second code. Therefore, the first code may be preferable in terms of memory usage.

However, the second code is more concise and easier to read since it uses a single line of code with two replace method calls instead of multiple if-else statements. This makes it more maintainable and easier to modify in the future.

Ultimately, the choice between the two codes may depend on the specific needs and constraints of the program or application, such as performance and memory usage requirements.

Thanks for reading 😁.Happy learning