02. Copy - Paste

#include <iostream>
#include <string>
#include <sstream>
#include <vector>
#include <stack>

using namespace std;

void makeSelection(int& startIndex, int& endIndex, const string &text)
{
    int fromIndex = startIndex;
    int toIndex = endIndex;

    for (int i = fromIndex; i > 0; --i)
    {
        if (text[i - 1] == ' ')
        {
            break;
        }
        startIndex--;
    }
    for (int i = toIndex; i < text.size(); ++i)
    {
        if (text[i] == ' ')
        {
            break;
        }
        endIndex++;
    }
}

void copy(vector<string>& copyCommand, const string& copyText, stack<string>& clip)
{
    string& fromIndexInString = copyCommand[1];
    int from = stoi(fromIndexInString);
    string& toIndexInString = copyCommand[2];
    int to = stoi(toIndexInString);

    makeSelection(from, to, copyText);

    clip.push(copyText.substr(from, to - from));
}

void paste(vector<string>& pasteCommand, string& pasteText, stack<string>& clip)
{
    string& indexInString = pasteCommand[1];
    int index = stoi(indexInString);

    if (!clip.empty())
    {
        if (pasteText[index] != ' ')
        {
            pasteText.insert(index, clip.top());
        }
        else
        {
            string current = clip.top();
            current.insert(0, " ");
            pasteText.insert(index, current);
        }
        clip.pop();
    }
}

void makeOperation(string& text, string& command)
{
    stack<string> clipboard;
    getline(cin, command);
    while (true)
    {
        if (command == "end")
        {
            break;
        }

        vector<string> vec;
        string word;
        istringstream istr(command);

        while (istr >> word)
        {
            vec.push_back(word);
        }
        const int size = vec.size();
        if (size == 3)
        {
            copy(vec, text, clipboard);
        }
        else
        {
            paste(vec, text, clipboard);
        }

        getline(cin, command);
    }
}

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

    string operation;

    makeOperation(inputText, operation);

    cout << inputText << endl;

    return 0;
}