import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArrayList;

public class TreeNodes {
  public static void main(String[] args) {
    test();
  }

  //測試removeSons方法
  public static void test(){

    //原始的Map
    Map<Integer, Integer> t=new HashMap<Integer, Integer>();
    //  ID PID
    t.put(1, 0);
    t.put(2, 1);
    t.put(3, 1);
    t.put(4, 2);
    t.put(5, 4);
    System.out.println("—— —— —— —— —— ——原始的Map —— —— —— —— —— —— ——");

    Set<Integer> keys=t.keySet();
    Iterator<Integer> iterator=keys.iterator();
    System.out.println("ID —— PID");
    while(iterator.hasNext()){
      Integer i=iterator.next();
      System.out.println(i+" —— "+t.get(i));  
    }

    int k=2;
    //遞歸刪除k的所有子節(jié)點(diǎn)
    System.out.println("—— —— —— —— —— ——刪除掉的節(jié)點(diǎn) —— —— —— —— —— —— ——");
    removeTreeNodes(t,k);
    //刪除k節(jié)點(diǎn)本身
    t.remove(k);
    System.out.println();
    System.out.println("—— —— —— —— —— —— 遞歸刪除["+k+"]的所有子節(jié)點(diǎn)后的Map —— —— ");

    iterator=keys.iterator();
    System.out.println("ID —— PID");
    while(iterator.hasNext()){
      Integer i=iterator.next();
      System.out.println(i+" —— "+t.get(i));
    }
  }

  //遞歸刪除所有的子節(jié)點(diǎn)
  public static Map<Integer, Integer> removeTreeNodes(Map<Integer, Integer> t,Integer k){ 
    //所有需要刪除的子節(jié)點(diǎn)
    List<Integer> sons=new ArrayList<Integer>();
    sons.add(k);
    List<Integer> temp=new ArrayList<Integer>();
    //循環(huán)遞歸刪除，所有以k為父節(jié)點(diǎn)的節(jié)點(diǎn)
    while(true){    
      for(Integer s:sons){
        Set<Integer> keys=t.keySet();
        Iterator<Integer> it=keys.iterator();
        while(it.hasNext()){
          Integer n=it.next();
          //如果父節(jié)點(diǎn)（即Map的value）為需要刪除的節(jié)點(diǎn)，則記錄此節(jié)點(diǎn)，并在Map中刪除
          if(t.get(n)==s){
            temp.add(n);
            it.remove();
            System.out.println("刪除了ID=["+n+"]的節(jié)點(diǎn),其父節(jié)點(diǎn)為["+s+"]");
          }
        }
      }

      //如果此節(jié)點(diǎn)包含子節(jié)點(diǎn)，則將子節(jié)點(diǎn)賦值給sons;否則表示所有子節(jié)點(diǎn)已經(jīng)刪除，結(jié)束循環(huán)
      if(temp.size()>0){
        sons=temp;  
        temp=new CopyOnWriteArrayList<Integer>();
      }else{
        break;
      }
    }

    return t;
  }
}

CREATE TABLE treeNodes
(
 id INT PRIMARY KEY,
 pid INT
);
INSERT INTO treeNodes VALUES 
(1, 0),
(2, 1),
(3, 1),
(4, 2),
(5, 4);

DELIMITER//

DROP PROCEDURE IF EXISTS removeTreeNodes//

CREATE PROCEDURE removeTreeNodes(IN rootid INT)
 BEGIN
 DECLARE LEVEL INT ;
 DROP TABLE IF EXISTS tempNodes;
 CREATE TABLE tempNodes (
  id INT,
  nLevel INT,
  sCort VARCHAR(8000)
 );
 SET LEVEL=0 ;
 INSERT INTO tempNodes SELECT id,LEVEL,ID FROM treeNodes WHERE PID=rootid;
 WHILE ROW_COUNT()>0 DO
  SET LEVEL=LEVEL+1 ;
  INSERT INTO tempNodes 
  SELECT A.ID,LEVEL,CONCAT(B.sCort,A.ID) FROM treeNodes A,tempNodes B 
  WHERE A.PID=B.ID AND B.nLevel=LEVEL-1 ;
 END WHILE;
 END;
//
DELIMITER ;

CALL removeTreeNodes(0);

SELECT CONCAT(SPACE(B.nLevel*2),'+--',A.id)
FROM treeNodes A,tempNodes B 
WHERE A.ID=B.ID 
ORDER BY B.sCort;