字典序法

import java.util.Scanner; public class Test4 { /** * @param args */ public static void main(String[] args) { // TODO 自动生成方法存根 Test4 a = new Test4(); Scanner input = new Scanner(System.in); System.out.print("请输入要排列的元素有多少种:"); int count = input.nextInt(); int[] p = new int[count]; for (int i = 1; i <= p.length; i++) { p[i-1] = i; } boolean con; do { a.pr(p);//输出排列p con = a.next(p);//求出按字典序排列的下一个排列p } while (con); } public int indexof(int[] n) { int index = -1; for (int i = n.length - 1; i >= 1; i--) { if (n[i-1] < n[i]) { index = i - 1; break; } } return index; } public int indexmin(int ini, int[] n) { int index = n.length - 1; int min = n[ini + 1]; for (int i = ini + 1; i < n.length; i++) { if (n[i] <= min && n[i] > n[ini]) { min = n[ i ]; index = i; } } return index; } public void swap(int index1, int index2, int[] n) { int temp; temp = n[index1]; n[index1] = n[index2]; n[index2] = temp; } public void oppositeDirection(int index1, int[] n) { for (int i = index1 + 1, j = n.length - 1, k = 0, temp; k <= (n.length - i) / 2; i++, j--, k++) { temp = n[i]; n[i] = n[j]; n[j] = temp; } } public boolean next(int[] n) { int index1 = indexof(n); if (index1 == -1) { return false; } int index2 = indexmin(index1, n); swap(index1, index2, n); oppositeDirection(index1, n); return true; } public void pr(int[] n) { for (int i = 0; i < n.length; i++) { System.out.print(n[i] + " "); } System.out.println(); } }