Step by Step solution about How to resolve the algorithm Determine if a string is squeezable step by step in the C++ programming language

The C++ code performs a squeeze operation on a string, removing consecutive occurrences of a specified character while preserving the remaining characters.

Detailed Explanation:

1. Template Function squeeze:

   • Parameters: Takes a string (std::basic_string) and a character (char_type).
   • Purpose: Removes consecutive occurrences of the specified character from the string.
   • Implementation:
     • Uses std::unique to iterate over the string characters.
     • The lambda function [ch](char_type a, char_type b) { return a == ch && b == ch; } checks for consecutive occurrences of the character ch.
     • The iterator i points to the first character after the last consecutive occurrence.
     • The string is then truncated to length i - str.begin(), effectively removing the consecutive occurrences.

2. Function test:

   • Parameters: A string and a character.
   • Purpose: Tests the squeeze function for a given string and character.
   • Implementation:
     • Prints the original string and its length.
     • Calls squeeze to remove consecutive occurrences of the character.
     • Prints the squeezed string and its length.

3. Main Function:

   • Calls test on multiple string and character combinations to demonstrate the squeeze operation.
   • Tests various cases, such as empty strings, strings with consecutive characters, strings with multiple occurrences of the character, and strings with leading/trailing whitespace.

Output:

The output shows the original strings, their lengths, and the squeezed strings after removing consecutive occurrences of the specified character.

For example, the test case:

test("..1111111111111111111111111111111111111111111111111111111111111117777888", '7');

will produce the following output:

character: '7'
original: <<<..1111111111111111111111111111111111111111111111111111111111111117777888>>>, length: 82
result: <<<..1111111111111111111111111111111111111111111111111111111118>>>, length: 49

The original string has a sequence of consecutive '7' characters. After squeezing, only one '7' remains.

#include <algorithm>
#include <string>
#include <iostream>

template<typename char_type>
std::basic_string<char_type> squeeze(std::basic_string<char_type> str, char_type ch) {
    auto i = std::unique(str.begin(), str.end(),
        [ch](char_type a, char_type b) { return a == ch && b == ch; });
    str.erase(i, str.end());
    return str;
}

void test(const std::string& str, char ch) {
    std::cout << "character: '" << ch << "'\n";
    std::cout << "original: <<<" << str << ">>>, length: " << str.length() << '\n';
    std::string squeezed(squeeze(str, ch));
    std::cout << "result: <<<" << squeezed << ">>>, length: " << squeezed.length() << '\n';
    std::cout << '\n';
}

int main(int argc, char** argv) {
    test("", ' ');
    test("\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln ", '-');
    test("..1111111111111111111111111111111111111111111111111111111111111117777888", '7');
    test("I never give 'em hell, I just tell the truth, and they think it's hell. ", '.');
    std::string truman("                                                    --- Harry S Truman  ");
    test(truman, ' ');
    test(truman, '-');
    test(truman, 'r');
    return 0;
}