package study; // 순열 : nPr // 도움 : https://gorakgarak.tistory.com/522?category=265216 public class Permutation { public static void main(String[] args) { int[] array = {1, 2, 3, 4}; permutation(array, array.length, 2, 0); } public static void permutation(int[] arr, int n, int r, int depth) { if (depth == r) { // 종료 조건 print(arr, r); return; } for (int i = depth; i < n; i++) { swap(arr, i, depth); permutation(arr, n, r, depth+1); swap(arr, i, depth); } } public static void swap(int[] arr, int i, int j) { int temp = arr[i]; arr[i] = arr[j]; arr[j] = temp; } public static void print(int[] arr, int length) { for (int i = 0; i < length; i++) { if(i == length - 1) { System.out.println(arr[i]); } else System.out.print(arr[i] + ","); } } }