Solution: Shape Game (Stacks and Coding)

#include <iostream>
#include <stack>
using namespace std;

int main ()
{
    string s; // the sequence of characters describing the game's events
    int score = 0;
    cin >> s;
    
    // Use a stack to keep track of the pile of shapes
    stack<char> shapes;
    
    // Process each event in the sequence
    for (int i = 0; i < s.length(); i++) {
        char event = s[i];
        
        if (event == 'S' || event == 'C') {
            // A shape arrives - push it onto the stack
            shapes.push(event);
        }
        else if (event == 'L') {
            // Child presses L button (expecting a square)
            if (!shapes.empty()) {
                if (shapes.top() == 'S') {
                    // Correct! Square on top
                    score++;
                    shapes.pop();
                }
                else {
                    // Wrong! Circle on top
                    score--;
                }
            }
            // If empty, nothing happens
        }
        else if (event == 'R') {
            // Child presses R button (expecting a circle)
            if (!shapes.empty()) {
                if (shapes.top() == 'C') {
                    // Correct! Circle on top
                    score++;
                    shapes.pop();
                }
                else {
                    // Wrong! Square on top
                    score--;
                }
            }
            // If empty, nothing happens
        }
    }
    
    cout << "The score is " << score << endl;
    return 0;
}