「java求所有子集」java 子集
今天给各位分享java求所有子集的知识，其中也会对java 子集进行解释，如果能碰巧解决你现在面临的问题，别忘了关注本站，现在开始吧！
本文目录一览：
JAVA递归找所有子集
package web;
import java.util.ArrayList;
public class SubsetGenerator
{
int[] indexs = null;
int COUNT = 1;// choose how many to be combination
ArrayListString list = new ArrayListString ();
private String subsets;
public SubsetGenerator( String subsets )
{
this.subsets = subsets;
}
public ArrayListString getSubsets ( int... params )
{
if(params.length == 0)
{
indexs = new int[subsets.length ()];
params = new int[2];
params[0] = 0;
params[1] = -1;
list.add ("");
}
params[1]++;
if(params[1] COUNT - 1)
{
return list;
}
for( indexs[params[1]] = params[0]; indexs[params[1]] subsets.length (); indexs[params[1]]++ )
{
getSubsets (indexs[params[1]] + 1, params[1]);
if(params[1] == COUNT - 1)
{
String temp = "";
for( int i = COUNT - 1; i = 0; i-- )
{
temp += subsets.charAt (indexs[params[1] - i]);
}
list.add (temp);
}
}
if(COUNT subsets.length () params[0] == 0)
{
COUNT++;
getSubsets (0, -1);
}
return list;
}
}
package web;
import java.util.ArrayList;
import java.util.Collections;
public class SubsetGeneratorTester
{
public static void main ( String[] args )
{
SubsetGenerator generator = new SubsetGenerator ("rum");
ArrayListString subsets = generator.getSubsets ();
Collections.sort (subsets);
if(!"[, m, r, rm, ru, rum, u, um]".equals (subsets.toString ()))
{
System.err.println ("Expected: [, m, r, rm, ru, rum, u, um]");
}
else
{
System.err.println ("Congratulations !");
System.out.println ("Your result is: " + subsets);
}
}
}
用递归 求出一个string的所有子集 java
其实问题还是比较明显的，比如subsets.add(firstWord);这句话在for循环中重复执行，但是显然firstWord每次都是word.substring(0, 1);而在整个for循环中，你又没有对word重新赋值过。这也就是为什么你的输出有那么多相同的字符串吧
另外，理论上你每次新建一个SubsetGenerator，就不能算递归了
public static ArrayListString getSubSequences(String word) {
ArrayListString list = new ArrayListString();
doGetSubSequences(word, "", list);
return list;
}
private static void doGetSubSequences(String word, String s,
ArrayListString list) {
if (word.length() == 0) {
list.add(s);
return;
}
String tail = word.substring(1);
doGetSubSequences(tail, s, list);
doGetSubSequences(tail, s + word.charAt(0), list);
}
java树级对象递归查找子集问题
package com.demo.dept;
/**
* @author dongbin.yu
* @from 2016-05-06
* @since V1.0
*/
public class Dept {
private int id;
private String name;
private int parentId;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getParentId() {
return parentId;
}
public void setParentId(int parentId) {
this.parentId = parentId;
}
public Dept(int id, String name, int parentId) {
this.id = id;
this.name = name;
this.parentId = parentId;
}
}
package com.demo.dept;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* @author dongbin.yu
* @from 2016-05-06
* @since V1.0
*/
public class DeptTest {
private static ListDept depts = new ArrayList();
static{
depts.add(new Dept(1,"部门1",0));
depts.add(new Dept(2,"部门2",1));
depts.add(new Dept(3,"部门3",1));
depts.add(new Dept(4,"部门4",1));
depts.add(new Dept(5,"部门5",2));
depts.add(new Dept(6,"部门6",3));
depts.add(new Dept(7,"部门7",2));
depts.add(new Dept(8,"部门8",2));
depts.add(new Dept(9,"部门9",1));
depts.add(new Dept(10,"部门10",5));
}
public static void main(String[] args) {
MapInteger, ListInteger deptMap = new HashMap();
for (Dept dept : depts) {
deptMap.put(dept.getId(),getChildDept(dept.getId()));
}
System.out.println(deptMap);
}
private static ListInteger getChildDept(int id){
ListInteger ids = new ArrayList();
for (Dept dept : depts) {
if(dept.getParentId() == id){
//添加第一次父id符合的
ids.add(dept.getId());
//添加嵌套父id符合的
ids.addAll(getChildDept(dept.getId()));
}
}
Collections.sort(ids);
return ids;
}
}
java求所有子集的介绍就聊到这里吧，感谢你花时间阅读本站内容，更多关于java 子集、java求所有子集的信息别忘了在本站进行查找喔。
发布于：2022-11-22，除非注明，否则均为原创文章，转载请注明出处。