有重复数的组合
package com.viking.divide;public class DuplicateCombination {public static void main(String[] args) {int[] a = { 1, 2, 3 ,3};System.out.println(perm(a, 0));}public static int perm(int[] a, int begin) {int count = 0;boolean isorder = true;String path = "";for (int i = 0; i < begin - 1; i++) {if (a[i] > a[i + 1]) {isorder = false;break;}path += a[i] + " ";}if (isorder && begin > 0) {System.out.println(path + a[begin - 1]);count = 1;}if (begin == a.length) {return count;}for (int i = begin; i < a.length; i++) {if(isSwap(a,begin,i)){swap(a, begin, i);count += perm(a, begin + 1);swap(a, begin, i);}}return count;}public static void swap(int[] a, int begin, int end) {int temp = a[begin];a[begin] = a[end];a[end] = temp;}public static boolean isSwap(int[] a,int begin,int end){for(int i=end;i>begin;i--){if(a[end]==a[i-1]){return false;}}return true;}}