LSD链式基数对数值排序BUG；列出串中有顺序的三个字符

import java.util.LinkedList;

import java.util.Random;

class Num{
private int pos1;
public int getPos1() {
return pos1;
}
public void setPos1(int pos1) {
this.pos1 = pos1;
}
public int getPos10() {
return pos10;
}
public void setPos10(int pos10) {
this.pos10 = pos10;
}
public int getPos100() {
return pos100;
}
public void setPos100(int pos100) {
this.pos100 = pos100;
}
public int getPos1000() {
return pos1000;
}
public void setPos1000(int pos1000) {
this.pos1000 = pos1000;
}
private int pos10;
private int pos100;
private int pos1000;
public  Num(int x) {
pos1=x%10;
pos10=((x%1000)%100)/10;
pos100=(x%1000)/100;
pos1000=x/1000;

}
public String toString() {
String str="";
if (pos1000!=0) {
str+=pos1000;
}
if (pos100!=0) {
str+=pos100;
}
if (pos10!=0) {
str+=pos10;
}
str+=pos1;
return str;
}

}

public class LSD_No_Position {

@SuppressWarnings("unchecked")
static void lsdSort(LinkedList<Num> lst) {
LinkedList[] digit=new LinkedList[10];
for (int i = 0; i < digit.length; i++)digit[i]=new LinkedList();//不清楚里面有多少个值，用LinkedList装
//分配
while (lst.size()>0) {
Num n=lst.remove();
digit[n.getPos1()].add(n);
}
//收集
for (int i = 0; i < digit.length; i++)
lst.addAll(digit[i]);

digit=new LinkedList[10];
for (int i = 0; i < digit.length; i++)digit[i]=new LinkedList();//不清楚里面有多少个值，用LinkedList装
//分配
while (lst.size()>0) {
Num n=lst.remove();
Num n2=n;
digit[n.getPos10()].add(n);
}
//收集
for (int i = 0; i < digit.length; i++)lst.addAll(digit[i]);

digit=new LinkedList[10];
for (int i = 0; i < digit.length; i++)digit[i]=new LinkedList();//不清楚里面有多少个值，用LinkedList装
//分配
while (lst.size()>0) {
Num n=lst.remove();
int x=n.getPos100();
digit[n.getPos100()].add(n);
}
//收集
for (int i = 0; i < digit.length; i++)lst.addAll(digit[i]);

digit=new LinkedList[10];
for (int i = 0; i < digit.length; i++)digit[i]=new LinkedList();//不清楚里面有多少个值，用LinkedList装
//分配
while (lst.size()>0) {
Num n=lst.remove();
int x1=n.getPos1();
int x10=n.getPos10();
int x100=n.getPos100();
int x1000=n.getPos1000();

digit[n.getPos1000()].add(n);
}
//收集
for (int i = 0; i < digit.length; i++)lst.addAll(digit[i]);

}
public static void main(String[] args) {
// TODO Auto-generated method stub
Random r=new Random();
LinkedList<Num> list=new LinkedList<Num>();
/* for (int i = 0; i < 5; i++) {
list.add(new Num(r.nextInt(10000)));
}*/
list.add(new Num(2740));
list.add(new Num(6263));
list.add(new Num(5156));
list.add(new Num(623));
list.add(new Num(9345));

lsdSort(list);
System.out.println(list);
}

}

以上代码用随机数放进去，结果未排序，但是换成随机生成对应的数放进去，结果就是排序的，求解，若解决的请站内联系

从键盘读入一个由字母构成的串（不大于30个字符）。从该串中取出3个不重复的字符，求所有的取法。取出的字符，要求按字母升序排列成一个串。

不同的取法输出顺序可以不考虑。

例如：

输入：

abc

则输出：

abc

输入：

abcd

则输出：

abc

abd

acd

bcd

输入：

abcaa

则输出：

abc

import java.util.ArrayList;

import java.util.HashSet;

import java.util.Iterator;

import java.util.List;

import java.util.Scanner;

import java.util.Set;

public class UniqueAlphaSort {
/**
* @param args
*/
@SuppressWarnings("unchecked")
public static void main(String[] args) {
Scanner scanner=new Scanner(System.in);
String str=scanner.nextLine();
Set alphaSet=new HashSet();
for (int i = 0; i < str.length(); i++) {
alphaSet.add(str.charAt(i));
}
List<Character> list=new ArrayList<Character>();
Iterator iterator=alphaSet.iterator();
while (iterator.hasNext()) {
list.add((Character)iterator.next());
}
//排序
for (int i = list.size()-1; i >0 ; i--) {
for (int j = 0; j < i; j++) {
if (list.get(j)>list.get(j+1)) {
char tmp=list.get(j);
list.set(j, list.get(j+1));
list.set(j+1, tmp);
}
}
}
for (int i = 0; i < list.size()-2; i++) {
for (int j = i+1; j < list.size()-1; j++) {
for (int j2 = j+1; j2 < list.size(); j2++) {
String x=list.get(i).toString();
String x1=list.get(j).toString();
String x2=list.get(j2).toString();
System.out.println(x+x1+x2);
}
}
}
}

}