Java 중복유무 순열 조합

 

 

 

import java.util.Arrays;
import java.util.LinkedList;
import java.util.Scanner;

public class main {
    static int[] arr = {1, 2, 3, 4};

    public static void main(String[] args) {
        int n = arr.length;

        //순서있는 모든 경우의 수
        LinkedList<Integer> perArr = new LinkedList();
        int[] perCheck = new int[n];
        for (int r = 0; r <= n; r++) {
            permutation(n, r, perArr, perCheck);
        }

        //중복할 수 있는 순서있는 모든 경우의 수
        LinkedList<Integer> rePerArr = new LinkedList<Integer>();
        for (int r = 0; r <= n; r++) {
            rePermutation(n, r, perArr);
        }

        //조합
        for (int r = 0; r <= n; r++) {
            int[] comArr = new int[r];
            combination(comArr, n, r, 0, 0);
        }

//        중복 조합
        for (int r = 0; r <= n; r++) {
            int[] reComArr = new int[r];
            reCombination(reComArr, n, r, 0, 0);
        }

    }

    private static void permutation(int n, int r, LinkedList<Integer> perArr, int[] perCheck) {
        if (perArr.size() == r) {
            for (int i : perArr) {
                System.out.print(i);
            }
            System.out.println();
            return;
        }

        for (int i = 0; i < n; i++) {
            if (perCheck[i] == 0) {
                perArr.add(i);
                perCheck[i] = 1;
                permutation(n, r, perArr, perCheck);
                perArr.removeLast();
                perCheck[i] = 0;
            }
        }
    }

    private static void rePermutation(int n, int r, LinkedList<Integer> rePerArr) {
        if (rePerArr.size() == r) {
            for (int i : rePerArr) {
                System.out.print(arr[i] + " ");
            }
            System.out.println();
            return;
        }

        for (int i = 0; i < n; i++) {
            rePerArr.add(i);
            rePermutation(n, r, rePerArr);
            rePerArr.removeLast();
        }
    }

    private static void combination(int[] comArr, int n, int r, int index, int target) {
        if (r == 0) {
            for (int i : comArr) {
                System.out.print(arr[i] + " ");
            }
            System.out.println();
            return;
        }
        if (target == n) return;

        comArr[index] = target;
        combination(comArr, n, r - 1, index + 1, target + 1);//뽑는경우
        combination(comArr, n, r, index, target + 1);//안뽑는경우

    }

    private static void reCombination(int[] reComArr, int n, int r, int index, int target) {
        if (r == 0) {
            for (int i : reComArr) {
                System.out.print(arr[i] + " ");
            }
            System.out.println();
            return;
        }
        if (target == n) return;

        reComArr[index] = target;
        reCombination(reComArr, n, r - 1, index + 1, target);//뽑는경우
        reCombination(reComArr, n, r, index, target + 1);//안뽑는경우

    }

 


}