Think Like a Coder: Scrambled Words Problem using C++

#include <bits/stdc++.h>

using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    string s;
    getline(cin, s);
    for (int i = 0; i < (int) s.size(); i++) {
        if ((s[i] >= 'A' && s[i] <= 'Z') || (s[i] >= 'a' && s[i] <= 'z')) {
            int decipher = s[i] - 3;
            if (s[i] >= 'a' && s[i] <= 'c') {
                int diff = 'a' - decipher - 1;
                s[i] = (char) ('z' - diff);
            } else if (s[i] >= 'A' && s[i] <= 'C') {
                int diff = 'A' - decipher - 1;
                s[i] = (char) ('Z' - diff);
            } else {
                s[i] = (char) (decipher);
            }
        }
    }
    vector<bool> visited((int) s.size(), false);
    for (int i = 0; i < (int) s.size() - 1; i++) {
        for (int j = i + 1; j < (int) s.size(); j++) {
            if (s[i] >= 'a' && s[i] <= 'z') {
                if ((s[j] < 'a' || s[j] > 'z') && (s[j] < 'A' || s[j] > 'Z')) {
                    break;
                }
            }
            if ((s[i] >= 'a' && s[i] <= 'z') && (s[j] >= 'a' && s[j] <= 'z') && !visited[i] && !visited[j]) {
                visited[j] = true;
                swap(s[i], s[j]);
                break;
            } else if ((s[i] >= 'A' && s[i] <= 'Z') && (s[j] >= 'A' && s[j] <= 'Z') && !visited[i] && !visited[j]) {
                visited[j] = true;
                swap(s[i], s[j]);
                break;
            }
        }
    }
    cout << s << '\n';
    return 0;
}