Algorithms. Daniil Skvortsov. 2 variants of the solution

CocktailSort.java

package program;


public class CocktailSort {
    public static void cocktailSort(int[] array) {
        int temp;
        int left = 0;
        int right = array.length - 1;
        do {
            for(int i = left; i < right; i++) {
                if(array[i] > array[i + 1]) {
                    temp = array[i];
                    array[i] = array[i + 1];
                    array[i + 1] = temp;
                }
            }
            right -= 1;
            for(int i = right; i > left; i--) {
                if(array[i] < array[i - 1]) {
                    temp = array[i];
                    array[i] = array[i - 1];
                    array[i - 1] = temp;
                }
            }
            left += 1;
        } while(left < right);
    }
}

Program.java

package program;


public class Program {

    public static int firstSolution(int[] array){
        CocktailSort.cocktailSort(array);

	      int firstEl = array[0];
	      for(int i = 1; i < array.length; i++)
            if(firstEl == array[i])
                return firstEl;
            else
                firstEl = array[i];

	      return -1; // Не может быть по условию задачи
    }
    
    // Алгоритм "черепахи и зайца" Флойда
    public static int secondSolution(int[] array){
        int tort = array[0];
        int hare = array[0];
        while(true){
            tort = array[tort];
            hare = array[array[hare]];
            if(tort == hare)
                break;
        }
        int point1 = array[0];
        int point2 = tort;
        while(point1 != point2){
            point1 = array[point1];
            point2 = array[point2];
        }
        return point1;
    }
    
    public static void main(String[] args) {
        int[] array = {1,3,4,3,4}; // Пользовательский ввод данных не реализован, чтобы не загромождать код
        int ans1 = firstSolution(array);
        int ans2 = secondSolution(array);
        System.out.println(ans1);
        System.out.println(ans2);
    }
    
}