Odd Even Index

import java.util.Scanner;

class Solution {

    // O(N) Time, O(N) Space - Optimal (Single Pass)
    public static void solve_odd_even_index() {
        Scanner scanner = new Scanner(System.in);
        if (!scanner.hasNextLine()) return;
        String S = scanner.nextLine();
        
        StringBuilder evenChars = new StringBuilder();
        StringBuilder oddChars = new StringBuilder();

        for (int i = 0; i < S.length(); i++) {
            if (i % 2 == 0) {
                evenChars.append(S.charAt(i));
            } else {
                oddChars.append(S.charAt(i));
            }
        }
        
        System.out.println(evenChars.toString());
        System.out.println(oddChars.toString());
        scanner.close();
    }

    public static void main(String[] args) {
        solve_odd_even_index();
    }
}

#include <iostream>
#include <string>
#include <sstream>

using namespace std;

// O(N) Time, O(N) Space - Optimal (Single Pass)
void solve_odd_even_index() {
    string S;
    // Read the entire line as the string
    if (!getline(cin, S)) return;

    string even_chars = "";
    string odd_chars = "";

    // Single Linear Pass (O(N))
    for (int i = 0; i < S.length(); ++i) {
        if (i % 2 == 0) {
            even_chars += S[i];
        } else {
            odd_chars += S[i];
        }
    }
    
    cout << even_chars << endl;
    cout << odd_chars << endl;
}

// O(N) Time, O(N) Space - Brute (Same fundamental approach)
void solve_odd_even_index_brute() {
    solve_odd_even_index(); 
}

int main() {
    solve_odd_even_index();
    return 0;
}