The Roadmap to Efficient Reversal and Filtering

The method we're discussing here is a universal tool for efficiently reversing any array or string. It's like the Swiss Army knife of reversals. Once you have a grip on this, the next challenge is merely a process of sifting out the non-alphabetical characters, almost like separating wheat from chaff.

Method 1: Isolate, Store, and Reverse

Step 1: Identify Alphabetical Characters

The first step is to identify only the alphabetical characters in the given string. Think of this as a treasure hunt where you only pick up the gold coins and leave the pebbles behind.

Step 2: Store Them Separately

Once you've identified these "gold coins," you store them in a separate array. Imagine placing the gold coins in a separate bucket.

Step 3: Execute the Reversal

After storing these alphabetic characters, the next action is to reverse them. You can use the two-pointer swap method we discussed earlier for this purpose.

Regex to the Rescue

Regular expressions (regex) can be a helpful tool for identifying the alphabetical characters. You can use a pattern like /[a-zA-Z]/ to spot these alphabetic "gold coins" amidst the string of diverse characters.

By following this method, you can isolate what you need, reverse it efficiently, and leave everything else undisturbed.

1std::regex r("[a-zA-Z]");
2
3for (char ch : str) {
4    if (std::regex_match(std::string(1, ch), r)) {
5        alphaChars.push_back(ch);
6    }
7}
8
9std::vector<char> reversedAlpha = reverseArray(alphaChars);