03. Replace Repeating Chars

#include <iostream>
#include <string>

using namespace std;

int main() {
    string str;
    getline(cin, str);

    int startIndex = 0, replacedLength = 0;

    for (size_t i = 1; i <= str.length(); i++) {
        if (str[startIndex] != str[i]) {
            startIndex++;
            replacedLength = i - startIndex;
            str.replace(startIndex, replacedLength, "");
            i = startIndex;
        }
    }

    cout << str << endl;
    return 0;
}

ИЛИ:

#include <iostream>
#include <string>

using namespace std;

int main() {
    string str;
    getline(cin, str);

    int startIndex = 0, replacedLength = 0;

    for (size_t i = 1; i <= str.length(); i++) {
        if (str[startIndex] != str[i]) {
            startIndex++;
            replacedLength = i - startIndex;
            str.erase(startIndex, replacedLength);
            i = startIndex;
        }
    }

    cout << str << endl;
    return 0;
}

ИЛИ:

#include <iostream>
#include <string>

using namespace std;

int main() {
    string str, result;
    getline(cin, str);

    result = str[0];

    for (size_t i = 1; i < str.length(); i++) {
        if (result[result.length() - 1] != str[i]) {
            result += str[i];
        }
    }

    cout << result << endl;
    return 0;
}